OK. You asked for it. Apparently,
you're interested in one of the more obscure or more specialized chemistry
terms. As such, I'm guessing you're either an undergrad with lots
of time on his/her hands or a graduate student desperately studying for
for cumes. I've been there, and as a public service to you guys, here's
a great big list of chemistry terms. I hope you enjoy reading them
as much as I enjoyed typing them.
|ab initio: from first
abscissa: the name given to the horizontal axis in a set of two-dimensional coordinates. Commonly referred to as the x-axis.
absorption filter: filter which allow all light through except for that in a narrow region; this is caused by the light being absorbed by the filter material.
ac arc: a method of vaporization and excitation in emission spectroscopy, using voltages of less than 5000 V. Results with this method are more reproducible than that possible with a dc arc.
acceleration slits: positively charged ions produced in an ionization chamber of a mass spectrometer are passed into the analyzer by the accleration slits. Generally, two acceleration slits are used; one has a slight negative potential with respect to the ionization chamber in order to attract the positive ions, and the other slit has an extremely high voltage which accelerates that ions to up to half the speed of light.
ac spark: put a charge of 40,000V across two electrodes; the electrons which flow between them will ionize the sample.
ACF: activated carbon fibers
adhesion: the force between unlike molecules
A*/E: low-field absorption/high-field emission with net absorptive character
aerosols: dispersions of liquids in gases and solids in gases.
afocal system: where both the object and image are focused at infinity. Primarily used in magnification, or when a beam needs to be expanded but not focused.
AIMD: ab inito molecular dynamics
allomorph: any of two or more crystalline forms of a substance
allotropic: variation of physical properties without change in substance. Example: graphite, charcoal and diamond are allotropes of carbon.
ALON: also known as Raytran, Al23O27N5, a glass used in IR spectroscopy
alpha-AgI: A form of silver iodide which is stable at high temperatures. It acts as a superionic material, conducting electricity effectively through ionic transport. Degrades below 147 C to beta-AgI.
alpha-electron: an electron in which the spin is +1/2
alpha particles: the helium nucleus.
aluminosilicates: silicates with aluminum occupying some of the silicon sites.
a-MCMB’s: Activated mesocarbon microbeads. Show ferromagnetism at low temperatures
ammeter: a device that measures current
ampholyte: a substance that may act as either an acid or a base
analyzer tube: a part of a mass spectrometer in which positive ions are separated according to their mass/charge ratios. In TOF, this part is straight, in others, curved.
angstrom: 10-10 meters.
anion photoelectron spectroscopy: what you do is hit a sample with a laser and create anions. A carrier gas takes the anions down to a magnetic-bottle time-of-flight photoelectron analyzer, where you can characterize them.
anisotropy: when something is not isotropic; you look at how much something is not random, and the measure of this non-randomness is the anisotropy.
annealing: the tempering of glass or metals by heat. Can also be used as a treatment for thin films to give them the desired properties.
annealing point: the temperature at which residual strain or stress in a glass will relieve itself in a few minutes.
annulene: totally conjugated hydrocarbon
anode: the electrode where oxidation occurs
antiferromagnetism: where there is no net magnetic moment because the spin magnetic moments are randomly oriented, canceling them.
antinodes: points of constructive interference between two waves
antireflection coating: increases energy transmitted through optical surfaces by reducing Fresnel reflection losses. The criteria for such a coating are that the refractive index of the material must be equal to the square root of the substrate index when the substrate is in air; also, the phase difference between the incident wave and reflected wave must be an odd multiple of pi.
anti-Stokes fluorescence: although most fluorescence complies with the Stokes law, a weak fluorescence is found at a shorter wavelength than the exciting wavelength. This additional energy is gained from excited vibrational levels within the ground state.
appearance potential: the potential required to get fragmentation ions in a mass spectrometer. Generally, this value is 1-4 eV greater than the value for the ionization energy of the corresponding molecular ion.
AR: antireflective coating
Archimedes principle: the buoyant force on a body immersed in a fluid is equal to the weight of the fluid displaced by that object.
armature: where the coils of wire are mounted on an electric motor
arsenic trisulfide: material used in IR windows (0.6-11 microns)
Arsenous acid: H3AsO3
ASED: atom superposition and electron delocalization: a method used in extended-Huckel calculations.
asphaltanes: heavy polyaromatics which are insoluble in n-hydrocarbon solvents, produced in oil refineries from the vacuum distillation of virgin crude oils and processed petroleum. They form unit sheets which are arranged in stacks; the number of unit sheets which join together and the height of these sheets is strongly solvent dependant.
astigmatism: when the lens is focused in one plane, but not in the plane 90 degrees to it.
atmosphere: 760 torr, 101.325 kPa
atomic absorption spectroscopy (AAS): ionize a sample, and then hit the ions with light and see where absorptions take place.
atomic emission spectroscopy (AES): heat a sample and it ionizes; measure the wavelengths of the relaxations of these ions.
atomic fluorescence spectroscopy (AFS): same as AAS, but you measure the wavelengths that pass through without being absorbed.
attenuator: used in e.s.r, the attenuation of the microwave power passing along a waveguide is achieved by means of a metal plate placed along the axis of the waveguide. The degree of attenuation increases as the plate is moved away from the wall of the waveguide toward the center. In IR and UV spectroscopy, the attenuator is a toothed comb, grid, or star arrangement introduced into one beam of a spectrometer, operated either automatically through an electronic servosystem, or manually to balance the radiation in both beams.
Auer burner: one source of radiation for far-IR spectroscopy. Consists of a thorium oxide mantle heated to ~2000K by a burning gas. Optimum wavelength is ~50 microns.
Auger effect: the emission of a second electron after high energy radiation has expelled another.
Auger electron spectroscopy: The use of the Auger effect to determine orbital energies and structure of the molecule.
autoprotolysis: solvent dissociation into anion and proton.
auxochrome: a saturated group with nonbonded electrons which, when attached to a chromophore, alters both the wavelength and intensity of an absorption.
azeotrope: some composition of a binary mix in which the two portions cannot be separated by distillation.
background region: the region of low transmission of a pass filter.
bar: 100 kPa
barrier-layer cell: a photoelectric detector which is made of iron coated with a semiconductor film; when light from 250-750nm hits this cell, you get a current; this is a cell which is mainly good for intense light sources, because there is not a huge signal enhancement.
basis set truncation error: the error you get in computational methods from not expanding an infinite series all the way to infinity. the more terms you use, the less basis set truncation error you get.
bathochromic shift: shift of an absorption to a longer wavelength due to substitution or solvent effect (red shift).
Bayer process: used to obtain aluminum from bauxite
BEEQ mass spectrometer: a type of mass spectrometer, where the B stands for the magnetic sector, E stands for the electric sector, and Q stands for the quadropole mass filter. All of these letters stand for devices which can be used to separate the ionic products into the desired types.
beta electron: an electron in which the spin is -1/2
beta particle: electron
bequerel: SI unit of radioactivity, equal to one disintegration per second.
Bernoulli’s principle: where the velocity of a fluid is high, the pressure is low, and vice-versa
bifurcation: division into two parts or branches or where these branches split apart
BIOGRAF: a computer program that allows the user to determine the positions of atoms or ions in biological molecules.
birefringence: when a single incident beam is split into two refracted beams. Both of the refracted beams are parallel, with one offset from the other.
bistability: when a system is able to exist in either of two steady states.
blaze wavelength: the wavelength or which the angle of reflection from the groove face of a grating and the diffraction angle are the same.
BLM: bilayer lipid membrane
Bohr radius: the radius of the n=1 orbital in hydrogen. .529exp(-10) m.
bolometer: an IR detector where changes in temperature of the responsive element due to incident radiation causes a change in conductivity of the element.
bonded phase chromatography (BPC): where the stationary phase of the analyte actually bonds to a solid surface; the solid surface usually consists of silica-based particles.
Born-Oppenheimer approximation: nuclei are so heavy that they stay essentially stationary during the timescale of electron transfer processes
Boudouard carbon: A form of carbon which is generated catalytically in the gas phase.
Bragg equation: relates the angles at which X-rays are scattered from a crystal to the spacing between the layers of molecules.
Brewster angle: used in laser rod windows, at this angle light polarized in one direction passes through with very little reflection. Can be used to control the polarization of light leaving a laser. Can be calculated using tan(thetaBrewster)=n of the refractive material (where n is the refractive index).
Brusselators cells: a theoretical system of oscillatory cells; useful because they can accurately model biological systems.
bulk modulus (K): defined as the ratio of hydrostatic pressure to fractional decrease in volume.
calcite: calcium carbonate
capacitor: a device for storing electric charge; consists of two conducting objects placed near each other but not touching; typically, when there is a voltage gradient between them, the energy can be kept stored until it needs to be discharged or until the voltage grows high enough that it spontaneously discharges.
carbon arc: a carbon electrode superheated so that it emits light. Good for producing IR radiation between 10-100 microns.
carbon filament atom reservoir: used in atomic spectroscopy, it enables materials to be examined without the use of highly flammable materials. When the sample is passed through a graphite tube under high voltage, it is atomized.
carrier gas: any gas used in a process which serves as a solvent for the chemical of interest. Useful in GC and other processes.
cascade process: the procedure for increasing the strength of a weak signal by the progressive build-up of electron displacement in a series of dynode plates in a photomultiplier.
CASSCRF: complete active space multiconfiguration self-consistent field; something that is incorporated into very complete ab initio molecular dynamics calculations.
catadiotropic systems: optical systems which contain both reflecting and refracting elements; handy for correcting aberrations over wide angular fields.
catenation: the linking of like atoms to form chains or rings.
cathode: electrode where reduction occurs
CBS: complete basis set
cellulose: a polysaccharide of glucose; the main component of plants.
centripetal force: the force which always points from a body in rotation to the center of rotation
CESR: conduction electron spin resonance
channeltron: a variant of the electron multiplier; used to enhance electron signals
CHARMM: a computatinal method for simulate protein dynamics in water.
chemical equivalence: when a nucleus or group of nuclei are related by a symmetry operation of the molecule and have the same chemical shifts.
chemical oxygen-iodine lasers (COIL): Lasers in which O2(a1deltag) generated chemically spurs the subsequent excitation of iodine atoms. Multi-kilowatt power possible.
chemical shift: the difference in the absorption spectrum of a particular proton from the absorption position of a reference proton.
chemical vapor deposition: use a vapor transport mechanism in which the gaseous reactants decompose and recombine to form some desired thin film. Decomposition and reaction are helped by having a heated substrate.
choke coil: a coil that has significant self-inductance
Christiansen filter: used as a bandpass filter, these filters transmit light where the refractive index of the material matches that of the light. This wavelength changes with temperature, so when using one of these filters the temperature must be kept roughly constant.
chromatic aberration: when the different wavelengths of light passing through a lens focus at different points. This effect arises from the fact that different wavelengths of light experience different refractive indexes when passing through a material.
chromophore: functional groups with characteristic optical absorptions or the molecules which contain them
CIDEP: chemically induced dynamic electron polarization
circular dichroism (CD): optically active materials absorb left and right circularly polarized light to different extents.
clathrate: a water cage that forms around a hydrocarbon in solution.
cloud chamber: A device which is used to determine which elementary particles are being generated in a nuclear reaction. What happens is that the elementary particles go zipping through a saturated water fog, and the ionized water molecules provide nucleation centers for the condensation of water. From following these tracks, the identities of the particles can be determined.
coexistance curve: a plot of density versus temperature for some substance. It measures the range over which the liquid and vapor phases can exist in equilibrium.
coherence length: how long it is before waves from a light source get out of step. The less wide the spread of radiation leaving the source, the longer the coherence length.
coherent Raman beat (CRB): an ESR technique in which you monitor the electron resonance using a single, weak microwave field. The purpose is to detect coherences between nuclear transitions that are in hyperfine contact with the unpaired electron spin.
cohesion: the force between like molecules
cold mirror: reflects visible and transmits IR light
collimated: forming a highly non-divergent beam
colloid: when large numbers of molecules swarm together due to intermolecular forces. The dispersed phase in a colloid has a huge surface area
coma: the variation of focal length with aperture.
combination bands: describes weak absorptions in IR spectra corresponding to the sum of two or more fundamental vibrational frequencies. These combination modes arise from the anharmonicities of the oscillators which leads to an interaction of the vibrational states in polyatomic molecules.
complex conjugate: the imaginary portion of some function f(x)
compression factor (Z): one way of determining how a gas deviates from ideality; Z=1 for ideal gases.
Compton effect: the observation that X-rays scattered off of materials have a lower frequency than the incident X-rays. Attributed to collisions between the X-rays and electrons.
conduction: the result of collisions between molecules; when one end of an object is heated, the molecules vibrate faster and the energy is transferred to their neighbors.
convection: when heat is transferred by the mass movement of molecules from one place to another.
Continuous flow stirred tank reactors (CSTR): Reactors in which reagents go in, are stirred, and products come out. May also be used for other purposes, such as coupling many reaction chambers to each other in a network.
copolymer: when two or more monomeric units of different type are strung togther into a polymer.
coprecipitation: when some precipitate contains an impurity within its bulk.
Coriolis force: used in rotating body problems, it is a pseudoforce that explains why bodies at the outer edge of a rotating disk experience higher linear speeds.
corner-cube prisms: also called retroreflectors, they have one corner of a cube which collects the light and returns it to the original source.
Corning 9753: calcium aluminosilicate; transmits from 0.3-4.6 microns
cornu mounting: a prism system employed in spectrophotometers in which radiation is passed in through one face of the prism and out through the opposite face. The prism employed for this purpose is formed from two thirty degree quartz prisms, one of right-handed quartz and one of left-handed quartz. Produces very good dispersion but no polarization.
COSMOSIL SPYE: a material used in HPLC columns. Good for separating fullerenes.
COSY: correlated spectroscopy; a two-D NMR technique.
coulombic attraction: the positive-negative attraction which takes place when you have two charged particles in close proximity
coulometric titration: a titration method in which the current passed through the sample is used to indicate completion of the reaction.
coupling constant: the separation between the peaks of a first-order multiplet produced as a result of spin-orbit coupling. The larger the value of J, the greater the coupling between the nuclei. J is usually measured in Hertz, and is not dependant on the operating frequency of the instrument.
CPMAS NMR: stands for charge polarized magic angle spinning nuclear magnetic resonance. Basically this is a method for taking molecules that have high degrees of spin and imparting some of that spin to molecules that have none. It’s handy for getting NMR signals off of atoms that usually do not have signals.
cross-product: A cross B = [A][B]sin(theta)
cryoscopic constant: used to measure the freezing point depression with the addition of a solvent.
curie: 3.7 exp10 nuclear disintegrations/sec.
Curie temperature: where a ferromagnetic transition occurs
CVD: chemical vapor deposition
cyclic voltammetry: a method for determining the kinetics of electrode processes. Current is monitored as the potential of the electrode is changed.
damped harmonic motion: when there is friction within an oscillating system, the amplitudes of the oscillation decrease over time due to this damping force.
dark current: the background current that flows in photoemissive and photoconductive detectors when no radiation is falling on the detector. It is a temperature-dependant effect, and can be decreased by many orders of magnitude by operating below -20C.
dc arc: put a voltage of 200-300 V across two graphite electrodes separated by about one centimeter; resulting heat causes ionization of the sample. This is commonly used in atomic absorption spectroscopy.
Debye temperature: the temperature above which a certain crystal behaves classically; the temperature above which thermal vibrations are more important than quantum effects
degeneracy: when one energy level corresponds to two or more states of motion. It arises when the symmetry of a molecule is such that certain fundamental frequencies are equal and is a common feature in IR spectroscopy.
deintercalation: the expulsion of a foreign atom from some crystal lattice where it has been residing (usually in interstitial spaces). The opposite of intercalation.
depolarization factor: by enclosing the sample tube in polarizing sheets, each line in a Raman spectrum can be split into a horizontal component and a vertical component. The depolarization factor is the ratio of these two components.
Devarda’s alloy: 50% Cu, 45% Al, 5% Zn; used to reduce inorganic nitrates and nitrites to ammonia.
dew point: when air containing a given amount of water is cooled, the temperature at which the partial pressure of water equals the saturated vapor pressure.
DFT: density functional theory
dialysis: the separation of small solute particles from colloid particles by means of a semi-permeable membrane.
diamagnetic: a diamagnetic material has no unpaired spins; when such a material without permanent dipoles has a magnetic field applied to it, the magnetic dipoles induced in the material line up opposite to that of the induced field.
diastereotopic: non-interchangeable protons; the chemical shift is not ever equivalent
dilute-spin species: when you have a species that is not very abundant; there is very little chance that there will be more than one magnetically-active isotope in a molecule.
dispersion: the spreading of white light into the full spectrum
diathermic: something that allows energy transfer as heat
distortion: departure of image shape from that predicted by first-order Gaussian optics; one example, when a rectangle is shaped like a pillow.
Doppler effect: the phenomena that the frequencies of waves are blue-shifted when the source moves toward the observer and red-shifted when the source moves away from the observer.
dot product: A dot B = AB cos (theta)
Dove prisms: used to rotate the image in optical systems
DQ: duroquinone, also known as tetramethyl-1,4-benzoquinone
drift region: the length that the charged ions travel through in a TOF mass spec.
ductility: how much strain a material will take before it breaks.
dynode: the anodes which are used to amplify the signal in photomultiplier tubes.
E/A*: low field emission/high field absorption with net absorptive character
ebullioscopic constant: used to measure the boiling point elevation of a solvent with the addition of a solute
effective nuclear charge: the net positive charge experienced by an electron in a many-electron atom.
effusion: the rate at which a gas escapes through an orifice or hole.
EHMO: extended Huckel molecular orbital
einsel lens: produces focusing without an overall change in the energy of the transmitted particle. A lens used in TOF mass spec devices.
einstein: the amount of energy absorbed by one mole of material undergoing a photochemical reaction
elastic deformation: the linear region on a strain versus stress plot where a material will still assume its original shape.
electrolytic cell: an electrochemical cell in which a non-spontaneous reaction is driven by an outside current
electron affinity: how much something wants to pick up electrons. A exothermic electron gain corresponds to a positive electron affinity.
electron gun: use a controlled beam of electrons striking a surface to elevate a local area to evaporation temperature; often used in manufacture of films by vapor deposition
electron impact (EI): a commonly-used mode in a mass spec where molecules in the vapor phase are bombarded with a high-energy electron beam. These impacts are recorded as a spectrum of positive ions separated on the basis of mass/charge (m/z).
electron magnetic resonance (EMR): covers a wide range of experimets including ESE, CRB, and others in the field of ESR.
electron spin echo (ESE): a method in which you initially hit your sample, and follow that up with other pulses to generate these spin echoes. An ESR technique.
electron spin echo envelope modulation (ESEEM): a method similar to CRB, except that you typically require three pulses instead of the one required by CRB.
electron spin resonance (ESR): Also known as electron paramagnetic resonance (EPR), this method is used to determine whether radicals are formed in solution. Although it is very useful at this purpose, the sensitivity toward determination of structure is poor. It is the study of molecules containing unpaired electrons by observing the magnetic fields at which they come into resonance with monochromatic radiation. The radiation is in the microwave region, and the magnetic fields are about .3 Tesla. It can be used to study radicals generated either through chemical reactions or radiation, as well as d-metal complexes and molecules in triplet states.
electron volt: corresponds to the energy acquired by an electron accelerated through a potential difference of one volt. 1eV corresponds to 1.602exp(-19)J.
electroosmosis: The process by which charged particles will tend to migrate toward a less charged area. Generally, when we think of this, we think of an electrolysis process where cations move in one direction, anions move in the other, and the net movement over the sample is zero. However, commonly there are areas of higher charge density, and the electroosmotic effect can greatly affect the behavior of the liquid.
electrostatics: the study of charges at rest
emulsion: dispersions of liquids in liquids, as in milk
enantiotopic: protons that are interchangeable through any symmetry operation (except rotation). The chemical shift is the same for these protons in an achiral environment.
ENDOR: electron nuclear double resonance; an ESR technique
epitaxial: the growth of one layer of crystals on another such that they have the same structure
escape depth: the maximum depth under a surface from which ionized electrons come
eutectic temperature: the temperature in a 2-component mixture where a liquid solution and both pure solids exist at a fixed pressure.
evanescent wave: a wave on the other side of a surface from a total internal reflection; decays exponentially with distance.
even function: a function in which f(x)=f(-x)
EXAFS: extended X-ray absorption fine structure
excimer: a combination of two atoms which survives only in an excited state and which dissolves as soon as the excitation has been lost
Excimer laser: A laser which is used to pump another laser, usually dye, laser.
expectation value: equal to the integral of (complex conjugate of psi)A(psi) d(tau). Gives the most probable value for that operator.
extensive property: any property that depends on the size of the system (m, V)
extraordinary ray: the beam that is deviant on being split by a birefringent crystal. It is parallel to the ordinary ray.
faraday: the total charge of a mole of electrons; 96,500 coulombs.
faraday cap: used as a collector for the direct detection of a current of charged particles
FEP: free energy perturbation
Fermi resonance: the term given to accidental degeneracy arising in polyatomic molecules in which two different vibrational states accidentally possess approximately the same energy and interact with each other.
ferromagnetism: when paramagnetic solids align such that the spins are oriented along the magnetic field.
first law of thermodynamics: the internal energy of a system is constant unless changed by doing work or heating.
flame emission spectroscopy (FES): burn the sample and measure the spectral lines emitted from the elements. This method is only good for doing an elemental analysis on elements that are easily excited.
flow injection analysis (FIA): when streams of reagents are mixed together and cause a chemical reaction which quickly passes into a detector; mostly handy for studying the dynamics of a reaction that happens on a microsecond timescale or more.
flame ionization detector: when you burn the gas coming out of a GC, any organics present will be ionized. Through the use of electrodes in a detector, the current caused from the presence of these ions can be measured with high sensitivity.
fluence: refers to the energy density from an optical souce impingent on a sample. The higher the energy density, the higher the fluence.
fluorescence: spontaneously emitted radiation which ceases immediately after exitation ceases. Comes from electonic transitions in which there is no change in multiplicity.
fluorolube: a mixture of fluorinated hydrocarbons used as a mulling agent for solids in IR spectroscopy, specially formulated to obtain the spectrum in which Nujol absorption bands appear.
fluorophor: any molecule in an excited state which is capable of exhibiting fluorescence.
force field: a kind of calculation which is used in molecular dynamics. The calculation is semi-empirical, which means that the wavefunctions of the system are not determined.
FRAP: fluorescence recovery after photobleaching
free inductance decay (FID): a measure of how fast magnetic relaxations take place; an exponentially decaying sine wave with the frequency equal to the difference between the applied frequency and the resonance frequency for that nucleus.
Fresnel lens: an aspheric lens whose surface is broken up into many concentric annular rings. Each ring refracts incident rays to a common focus, so that a very large-aperture and small f-number thin aspheric lens results. Not to be used for precision focusing applications.
fullerene onions: round fullerenes whith several layers of carbon on top of one another.
fullerenes: also called buckyballs, these are an elemental form of carbon consisting of some closed surface with no degrees of unsaturation. The most well-known of these is buckminsterfullerene, C60. Related to carbon nanotubes.
G2 calculations: an ab initio method for determining the entropies and enthalpies of reaction from the Schrodinger equation.
galvanic cell: electrochemical cell that produces electricity spontaneously
galvanometer: consists of a coil of wire suspended in the magnetic field of a permanent magnet. When current flows through this coil of wire, the magnetic field exerts a torque on the loop, which is opposed by a spring. When you attach a pointer to this coil, you get an analog readout of the current.
gangue: material of no value that accompanies the desired material in raw ores.
Gaussian broadening: when broadening comes from the varying Doppler shifts of emitting species in a gas.
geisser tubes: gas discharge tubes constructed to concentrate the discharge in a capillary tube joining two glass bulbs containing the anode and cathode. The tubes are operated by induction coils and produce intense glow discharges when small quantities of gases or vapors are contained inside the tube.
gel: a semi-rigid mass of a lyophilic sol in which the dispersion medium has been absorbed by the sol molecules
GEMC: the Gibbs Monte Carlo computer simulation technique; can use to simulate data on the coexisting vapor and liquid phases of a material at a given temperature.
geminate: united or arranged in pairs
geodesic: the shortest distance between two points on a sphere
g-factor: a measure of how much the spin magnetic moment interacts with the local magnetic field. Used in ESR.
glass transition: when a supercooled liquid becomes a glass; this is not a real phase change but represents a slowing down of the fluid relaxational motion to a point where the relaxation time is far greater than the time of observation. Not a sharp transition.
globar: emits radiation from 4-15 microns. Bonded SiC rod five cm. long and 5 mm. diameter operated at 1500K. Accurately simulates a blackbody emitter.
graft terpolymers: a polymer backbone onto which are grafted two series of chemically dissimilar sidechains. Depending on what these sidechains are, they can either order into periodic forms or remain microscopically mixed.
Gran plot: measures the volume of acid or base or any substance to be titrated versus the volume of titrant added.
half-wave plate: a crystal that rotates the polarization of light by 90 degrees.
Heisenberg uncertainty principle: (deltax)(deltap)>h/2pi; (deltaE)(deltat)>h/2pi
Helmholtz coil: an electromagnet wound around a charged-particle optical detector used to cancel out the effect of the earth’s magnetic field. Requires two coils.
Heterogeneous catalysis: A process where you have one material supporting the actual catalyst for a reaction. One common example is where a porous inorganic material (such as a zeolite) supports small metal particles. Through using small particles, you maximize the catalyst surface area, making it more efficient.
hexapole selection: a method by which molecules can be oriented in space; this can be used to set the up-down symmetry.
HFCC: hyperfine coupling constant
hohlraum: a laboratory device to produce blackbody radiation. Consists of a closed metal tube, blackened on the inside, with a narrow slit cut into one of the flat ends. On heating the tube the radiation escaping from the slit is virtually identical with that expected from a blackbody.
HOMCOR: homonuclear correlated spectroscopy; a 2-D NMR technique.
homotopic: protons that are interchangeable through an axis of symmetry. The chemical shift of these protons is the same in any environment.
hot mirror: reflect IR light and transmit visible.
HWOT: half-wave optical thickness
hydrodynamics: the study of fluid in motion
hyperchromic effect: an increase in absorption intensity; if structural modification leads to an increase in the molar extinction coefficient for a particular chromophoric group it is said to have brought about a hyperchromic effect.
hyperfine structure: the multiplet of peaks you see in the ESR spectrum. The source of this splitting is the magnetic field arising from nuclear magnetic momets within the molecule. Generally, for molecules with a spin of I, you see 2n+1 peaks coming from the splitting. The appearance of the peaks is governed by pascal’s triangle, much like the fine structure in NMR.
hyperpolarizability: the second order polarizability of a molecule. It describes how easily you can push or pull electrons around the molecule. A high hyperpolarizability is good if you want to detect second order processes like second harmonic generation.
hypochromic effect: a decrease in absorption intensity.
hypsochromic shift: the shift of an absorption to a shorter wavelength due to substitution or solvent effect (blue shift).
hysteresis: the tendency of a magnetic substance to remain in a certain magnetic condition
Hyugen’s principle: every point on a wave front can be considered as a source of tiny wavelets that spread out in the forward direction at the speed of the wave itself. The new wave front is the envelope of all these wavelets.
IAD: ion-assisted deposition; used to make optical coatings at low temperatures
IET: intramolecular electron transfer
immersion lens: a hemispherical lens which is used to decrease the detector size. Essentially, the image is reduced without loss of resolution.
incandescence: when materials are self-luminous solely owing to their high temperatures
inclusion: when something is incorporated in a crystal, either in a lattice site or interstitial site.
inertia: the tendency of a body to maintain its state of rest or uniform motion
infrasonic: sound waves with smaller frequency than we can hear (20 Hz)
intercalation: incorporation of a foreign atom into some crystal lattice (usually in the interstitial spaces)
intrinsic semiconductor: a material in which the band gap is small enough to make the material a semiconductor
Iodate ion: IO3(-)
ionic migration: A way of conducting electricity where you have charged particles moving through a matrix of some sort.
iris diaphragm: used in fluorimeters to control the amount of radiation from the source; consists of a series of overlapping plates arranged to move so that a roughly circular opening of variable size is produced. This is achieved by maintaining a nearly constant angle between the edges of adjacent plates.
Irtran 1: Magnesium fluoride
Irtran 2: zinc sulfide
isenthalpic: a change that occurs without a change in enthalpy
isotherm: a curve on a vol. vs. temp. vs. pressure diagram that corresponds to a single temperature
isotopomer: having the same topography
isotropic medium: a medium in which the waves travel at equal speed independantly of which direction they travel.
Jones reductor: a metal reductor column filled with zinc
joule: 1 kg sq.meter/sq. second
Kepler’s laws of planetary
Kjeldahl method: oxidize a sample to turn nitrogen gas to ammonium ions; used to determine the amount of nitrogen in a sample.
klystron: microwave generator
Knoop hardness: a static measure of material hardness based on the size of impression made in the material with a pyramidal diamond indenter under specific conditions.
Kronecker delta: when you take the integral over all space of a wavefunction and its complex conjugate, you get this. If it is equal to one, the wavefunctions are the same.
KRS-5: thallium bromoiodide
Lambertian radiator: when a light emitted from a source or scattered from a surface has a radiance that is independant of viewing angle
Lamb formula: used to find the shielding constants for nuclei.
laminar flow: when the neighboring layers of a moving liquid slide by each other smoothly
Langmuir-Blodgett film: lipid bilayer sorts of films. They can be made of any size and almost any thickness. They are plated on solid surfaces by taking these surfaces and dipping them into a container which has a liquid with the film floating on top.
Larmour frequency: precessional angular velocity of an atom. Equal to the product of the magnetogyric ratio and strength of the applied magnetic field.
laser desorption mass spectrometry (LDMS): when you take a sample and hit it with a laser, you send the particles that come flying off and send them into a mass-spec.
laser threshold damage level (LDT level): the intensity at which a laser will damage a surface; coated surfaces have a lower LDT level than uncoated surfaces. My dad did a lot of research on stuff like this.
latent heats: the heats of fusion and evaporation
lateral magnification: the height of an image divided by the height of the object
lattice energy: the energy required to separate completely the ions in an ionic solid.
law of universal gravitation: every particle attracts every other particle with a force that is proportional to the product of the masses and inversely proportional to the square of the distance between them.
leakage current: a current that travels along an unintended path
LEED: low-energy electron diffraction; can be used to investigate surface structures
length contraction: the idea that the length of an object is measured to be shorter when it is moving than when it is at rest. A consequence of relativity.
Lenz’s law: an induced emf always gives rise to a current whose magnetic field opposes the original change in magnetic flux.
LDOS: local density of states
linear polarizer: changes unpolarized light to polarized light.
linkage isomer: isomers where a ligand differs in which atom is bonded to the metal atom.
light pipe: a hollow cone with highly reflecting walls which collects light at one end and channels it through successive reflections to the other end. When the walls are changed to a highly absorptive material, it can be used as a light collector.
liquid crystal: a substance that has liquid-like long range disorder but some crystal-like aspects of short range order.
Littrow prism: used in laser cavities to select oscillation at a particular frequency. For a particular wavelength the refracted ray on entering the prism travels normally to the exit face. The exit face is reflectively coated so that this beam travels back along the original path.
longitudinal relaxation time (T1): the time it takes after a pulse in NMR for the nuclei to get the same spin up/spin down ratio they had before the pulse. Also called spin-lattice relaxation.
longitudinal wave: when the vibration of the particles in the medium move in the same direction as the motion of the wave, for example, a sound wave in air.
long-range coupling: an NMR term, this describes the fact that sometimes you get spin-spin coupling between protons over distances longer than three bond lengths. This usually happens in highly conjugated systems, and the coupling constants are generally less than 3Hz.
magnesia: magnesium oxide
magnetic equivalence: when a group of nuclei are chemically equivalent and have identical spin-spin interactions.
magnetogyric ratio: this is an empirical factor with which you can find the magnetic moment of a nucleus with a non-zero magnetic moment. It cannot be calculated because there is not enough knowledge about how the nucleus works.
masking agent: a chemical added to a mixture which will block any impurity from affecting the chemical analysis; this is very handy if you have a transition metal ion which may interfere with the analysis of another transition metal ion.
Maxsorb: A form of high surface area activated carbon manufactured by Kansai Coke and Chemicals, Japan.
MCT: mercury-cadmium-telluride detector. Used in doing IR spectroscopy.
mean free path: the average distance traveled by a gas molecule between collisions.
mechanical waves: waves that travel in a material medium, such as water waves.
mercury arc: an IR source that operates from 1-100 atmospheres. Good for producing IR radiation from 50-1400 microns.
mercury diffusion pump: in this sort of device, mercury is boiled to produce a very high vacuum. The principle working here is that the heated mercury vapor is dragging the molecules of gas in the system, and getting them out of the place you are trying to maintain a high-vacuum.
mesophase: a phase intermediate between liquid and solid. May also be a smectic phase.
metallofullerenes: fullerenes which contain metal atoms or ions in them. Commonly, many fullerenes are produced with metal impurities because the metal acts as a catalyst for their formation; this is especially true for nanotubes.
metal reductor column: a metal-filled column which is used to reduce metals in solution that are passed through it.
mica: potassium aluminosilicate
microgravimetry: When you go about trying to figure out the mass of something that doesn’t change much in weight. Usually you need very sensitive equipment that costs a lot.
microporous carbon: A form of carbon in which you see many small pores in the surface. Generally, the micropore walls consist of graphitic crystallites, causing them to have a hydrophobic nature.
mie scattering: similar to Rayleigh scattering, except that it is dependant on the shape of the particles.
Millipore filter: a water purification filter which has changeable filter cartridges. Depending on how pure the water needs to be, the filter sensitivity can be changed.
mixed conductor: A conductor in which both ionic migration and electrons or positive holes in the materials is responsible for current flow.
MLAR: multi-layer antireflection coating
moderator: a material used in a nuclear reactor to slow the neutrons; heavy water and graphite rods are two common materials.
modulus: a constant which expresses a force
Mohr titration: use of a chromate ion in a precipitation titration; endpoint is reached when the precipitate starts to form.
molar absorptivity: represents the absorbance of a 1M solution of analyte in a 1 cm. cell; used as a constant in Beer’s Law.
molecular beams: a narrow stream of molecules which is directed toward other molecules
molecular dynamics (MD): A way of figuring out how molecules will behave through the use of quantum mechanical methods. Different in form and method from semi-empirical methods such as the Monte Carlo method.
monochromator: light goes in, hits a dispersing element (such as a diffraction grating or prism) and some portion of light is allowed out the other side.
monodisperse: when a polymer has only one molecular mass. They are typically generated by natural processes.
Monte Carlo method: a semi-empirical method for determining molecular dynamics of a system. What you do is to move the particles via a random method. Whether or not this new configuration is accepted depends on 1) If the PE is not greater than before the change, it is accepted. 2) If it is accepted, it is accepted in proportion to how much the potential change is for all the particles in the system.
MOST: Korean Ministry of Science and Technology
mull: a finely ground powder dispersed in an oil for IR spectroscopy.
multimeter: a device that can measure voltage, current and resistance; may also be called a volt-ohm-meter (VOM)
multiplicity: Equal to 2S+1
b: A computer program that allows people to generate accurate structures for biomolecules
nanotube: A long cylindrical structure related to the fullerenes. The structure of these rods appears to be a stacked graphite ring structure on the outside, and a randomized graphitic crystal structure on the inside. Generally, these tubes form best at temperatures above 1200C, and not at all under 200C.
nascent: beginning to develop, immature.
Nd:YAG laser: A laser with a Nd/Yttrium aluminum garnet rod.
nebulizer: a way of producing an aerosol for AAS.
Neel temperature: where anti-ferromagnetic transitions occur
Nernst glower: produces IR light to 15 microns. A hollow rod about three centimeters long and one millimeter diameter made from ZrO2 and Y2O3 mixed with CeO2 or ThO2. Operated at temperatures from 1500-2000K.
Nernst heat theorem: entropy change of a transformation approaches zero as the temperature approaches zero
neutrino: a particle with no charge or mass that is given off during beta decay
newton: kg m/second squared; unit of force
Newton’s rings: when a curved glass surface is placed in contact with a flat glass surface, a series of concentric rings is observed when illuminated from above with monochromatic light. This is caused by the reflection of light from the surfaces, giving constructive and destructive interference. This phenomena can be used to test whether or not a lens is properly ground.
NIST: National Institute of Standards and Technology
nodes: points of destructive interference between two waves.
nonconservative field: describes the electric field produced by a changing magnetic field.
n-type semiconductor: donor band that is full donates to another empty band, giving rise to conductivity
nuclear quadrupole coupling constant: a molecular parameter which provides a sensitive probe of electronic and surrounding molecular structure near some quadrupolar nucleus of interest.
nucleation: when a small particle or molecule spurs the condensation of a vapor or solid. Can occur with solid or liquid particles, or even ions.
nujol: a high-boiling petroleum oil often used as a solvent for IR spectroscopy because it is relatively free of IR absorption bands.
observable: a physically-measurable property of a system
occlusion: when a impurity is “surrounded” by the material of interest, but not actually incorporated into the crystal lattice.
odd b: if g(-x)=-g(x), then g is an odd function.
off-axis chromatic aberration: when chromatic aberration results in a difference in image size.
Ohm’s law: V=I/R (voltage equals current/resistance)
operator: a rule that transforms a given function into another function
Opperman source: an IR source that consists of a ceramic tube with an internal noble metal heater. It requires no preheating.
optic axis: the direction in a birefringent crystal along which no splitting of the beam occurs
ordinary ray: the beam that does not deviate upon being split by a birefringent crystal
Ostwald process: a catalytic process which is used to make nitric acid from ammonia.
Ostwald ripening: coarsening in crystal structures; it is an inherent property of crystals at a solid-liquid interface. The coarsening and enarging of crystals at surfaces is driven by a thermodynamic driving force to reduce the surface to volume ratio; this in turn lowers the interfacial or line energy.
oxygen-free high-conductivity copper (OFHC): a form of copper used frequently for instrument applications because of high purity, good conductivity and resistance to hydrogen embrittlement.
PAH: polyaromatic hydrocarbon
paramagnetic: a paramagnetic material has unpaired electrons; when such a material which has molecules with permanent dipole moments is placed in an external field, they orient themselves. When there is no field, the molecules are randomly oriented.
parity operator: replaces each cartesian coordinate with its negative
parrafins: normal alkanes with no functionality and no branching.
pascal: newton/sq. meter
Pascal’s triangle: the diagram that gives the peak intensity ratios for NMR and ESR. It does have the appearance of a triangle, and each row has numbers which correspond to the sum of the numbers on top of it.
passband: the primary wavelength interval of transmission of a gas filter.
pellicles: beam-splitting mirrors made of high-tensile-strength polymer stretched over a flat metal surface
pencil angle: a half angle which describes the rays emanating from a point at the edge of an object
Penta prisms: deviate a ray of light by 90 degrees without inversion or reversion. Called penta prisms because they are pentagonal solids.
PES: potential energy surface
phase velocity: the velocity at which the crests of a wave move.
phonon: a lattice vibration
phosphorescence: spontaneous emission persists for a long time after the exciting radiation ceases. This long-lived relaxation arises from the fact that the transition being made here is a forbidden inter-system crossing.
photoconductive detector: a change in number of incident photons causes a fluctuation in the number of free charge carriers in a semiconductor. Electrical conductivity is inversely proportional to the number of incident photons.
photoelastic effect: sensitivity of the optical dielectric response to changes in density.
photoelectric effect: ejection of electrons from metals when exposed to UV radiation.
photoelectron spectroscopy (PES): measures the ionization energies of molecules when electrons are ejected from different orbitals; it uses these to infer the orbital energies. UV photoelectron spectroscopy is for hitting more energetic molecules, and X-Ray photoelectron spectroscopy is handy for pulling off the core electrons.
photomultiplier tube (PMT): when light comes in, it hits an anode surface that releases many electrons. When nine of these are placed in series, there is a huge increase in the original signal. The anode surfaces are called dynodes.
photosensitized reaction: when the reagent is not actually what absorbs light; instead, a photosensitizer picks up light and transfers the energy to the reagents.
photovoltaic detector: a change in the number of photons incident of a p-n junction causes fluctuations in the voltage generated by the junction.
physical vapor deposition (PVD): get a source material into the vapor phase and then allow the molecules to condense on the surface of a thin film
piezoelectric effect: the phenomenon in which a crystal under the action of a mechanical stress becomes electrically charged, with opposite charges at the two ends of the crystal. Does not occur in centrosymmetric crystals, except for those in the cubic 432 group.
plastic deformation: the strain at which a solid can no longer regain its original shape.
Pockel’s cell: an optical phase modulator
Poise: the cgs unit of viscosity; equal to dyne*sec/centimeters squared
polyampholyte: when a macromolecule has mixed anion and cation character.
polydisperse: When a polymer exists over a wide range of molecular masses; characteristic of man-made polymeric materials.
polymorph: the varying structures of solid materials when the temperature is changed
Poynting vector: the energy an EM wave transports per unit time per unit area. Denoted as the vector S.
pressure amplitude: represents the maximum and minimum amounts by which the pressure varies from normal ambient pressure. Usually used in describing shock waves or sound waves.
primary creep: when you put strain on a substance, this is the movement that is still recoverable.
proton decoupling: when you are doing C-NMR, you have the possibility that the spins of the carbon and that of the protons will couple, and the spectrum would then be very hard to understand. In this method, you get rid of any coupling by following the initial pulse with a pulse that randomizes the spins of the protons; in this way, the signal averaging gets rid of any spin coupling between them. It does make it easier to see how many carbons there are, although it makes it impossible to integrate peak heights to figure out the abundances of each equivalent carbon.
p-type semiconductor: low-lying acceptor band gives rise to conductivity
pulsed gradient spin echo (PSGE): An NMR technique which is used to study the speed of liquid motion.
pyranose: a six-membered ring sugar molecule.
pyrolytic: breaking apart through heat
pyromagnetic: when you can change magnetic properties of a compound through heating
quadrupole: a “double dipole”; a molecule with a quadrupole will have no dipole moment because the two dipoles present in the molecule cancel each other out. A good example is carbon dioxide.
quadrupole mass filter: used in mass spec, this tool has four voltage-carrying rods which serve to give ions which travel between them oscillations. Only ions with the right mass/charge ratio (m/z) can undergo these oscillations without hitting one of these rods.
quantum number: 1) n is the principal quantum number. n has possible values of 1,2,3... 2) l is the orbital quantum number, having values of 0....n-1 3) ml is the magnetic quantum number, having values of -l, -l+1....l 4) ms is the spin quantum number, having a value of either 1/2 or -1/2.
quarter wave plate: used to change linearly polarized light to circularly polarized light
Q-value: the total energy released by the radioactive disintegration of a nucleus
QWOT: quarter-wave optical thickness
radiant power: total amount of energy emitted by a light source per second
Rayleigh scattering: when light is scattered by particles much smaller than the wavelength. The shorter the wavelength, the more intense the scattering.
RC circuit: a circuit that uses both resistors and capacitors
reactive plasma deposition (RPD): similar to CVD, except that an rf plasma helps the decomposition/recombination process of the reactants.
rectifier: a device that turns ac power into dc power
reduced mass: =m1m2(m1+m2)
refractory metals: include tungsten, tantalum and molybdenum; used for electrode materials because they have a low, uniform surface potential, do not oxidize, and are bakeable
relativity principle: the basic laws of physics are the same in all inertial reference frames
relaxation times: consist of T1 (longitudinal relaxation time) and T2 (transverse relaxation time). Basically, the relaxation times correspond to the time it takes after the pulse in NMR or other spectroscopic tecniques for the molecules to go back to their Boltzmann distribution of states.
REMPI: resonance enhanced multi-photon ionization
resistance thermometer: uses the dependance of electrical resistance on temperature to measure the temperature.
resolution (of a lens): the ability of a lens to produce distinct images of two point objects very close together
resonance: what happens when you have two or more oscillators connected in some way; these oscillators tend to get the same frequency because this gives more efficient energy transfer between them. This coupling of frequencies is resonance.
resonant two-photon ionization (R2PI): A process in which two photons strike a sample and ionize the molecules. One good thing about this process is that the product ions generally have known structure.
rest mass: the mass of an object as measured in a reference frame where it is at rest.
Reststrahlen filter: utilizes the phenomena that reflections of white light from crystal surfaces will contain only one region of the spectrum
resultant: the sum of two or more vectors.
retroreflector: see corner-cube prism
reversion: right-to-left reversion of an image
Reynold’s number: characterizes the onset of turbulence in a tube. Re = 2vr(rho)/n, where n=viscosity, r=radius of tube, rho=density of the fluid, v=velocity of the fluid; If Re<2000, there is laminar flow; if Re>2000, there is turbulent flow.
RHME: rotating hanging meniscus electrode
rhomboid prism: used for lateral deviation of a light ray
rolling friction: the friction from when one body rolls across a surface; generally much smaller than the sliding friction.
root-mean-square speed (rms): the square root of the average of the squared speeds of gas molecules in a sample.
Roots blower: a type of vacuum pump capable of pressures down to .01 torr.
rotating disk electrode (RDE): method to determine kinetics of electrodes. If you have the electrode be a rotating disk, the current of the sample can be related to the speed of rotation.
Rowland ghosts: spurious intensity maximum spurred from periodic errors in the spacing of the ruled grooves in a diffraction grating.
RPM: radical pair mechanism
ruby: aluminum oxide, Al2O3
SAM: self-assembled monolayer
sapphire: Al2O3, aluminum oxide
SATP: standard ambient temperature and pressure; corresponds to 25 C, 1 bar
scalar: a quantity that is specified completely by giving a number
SCE: standard calomel electrode
Schott IRG 11: calcium aluminate; transmits light between .3-5.5 microns
Schott IRG 2: germanate; transmits light between .3-4.6 microns
Schott IRG N6: calcium aluminosilicate; transmits light between .3-4.75 microns
SCRF: self-consistent reaction field method. A method for calculating the energies of molecules in a reaction
second law of thermodynamics: the entropy of an isolated system increases in the course of a spontaneous change
Seeback effect: when a metal has a temperature gradient, it has a voltage. The difference in thermally induced voltages of two metals will cause a net voltage in a junction.
SERR spectroscopy: surface-enhanced resonance Raman spectroscopy; a Raman method used because it has excellent selectivity to the microscopic environment and orientation of things adsorbed on surfaces.
SERS: surface-enhanced Raman scattering
SHE: standard hydrogen electrode; defined as having 0V.
shear modulus: the modulus of rigidity; concerned with the elastic deformation of a body in which an applied force results in the shape of a body.
SHG: second harmonic generation
shielded: when the sigma value in NMR is greater than zero. Deshielding is when the value is less than zero.
silicon controlled rectifier: a switching device; in the on state it has low resistance and in the off state it has very high resistance.
size exclusion chromatography (SEC): where you separate mixtures based on the sizes of the molecules.
SLAR: single layer antireflection coating
smectic: a smectic phase is when the molecules align themselves into a pseudo-crystalline lattice. Liquid crystals are one example.
Snell’s law: n1sin(theta1)=n2sin(theta2); describes refraction.
softening point: the point at which a glass can be molded or worked
sol: a stable dispersion of either solids in liquids or solids in solids.
solenoid: a long coil of wire consisting of may loops; when current flows through it, the magnetic field resembles that of a bar magnet.
space-charge effect: used to describe particle beam aberrations, it arises from the natural repulsion of particles of like charge; a focused beam will disperse, giving a diffuse image.
spatial coherence: how much the waves are in step as they leave a laser cavity.
special theory of relativity:
specific gravity: the ratio of the density of a substance at 4 C to that of water at 4 C.
speed of sound: equal to the square root of the bulk modulus/density of the medium. As temperature rises, so does the speed of sound.
sphere: radius=4pi(r squared), volume=4/3pi(r cubed)
spherical aberration: the variation of focus with aperture in which a ray through the edge of the lens intersects the axis at a point other than the paraxial focus.
spinel: magnesium aluminate, MgAl2O4.
spin-spin coupling constant (J): defines how much of an interaction you have between nuclei in a molecule. Gives rise to the fine structure in NMR.
SPT: sputtering; allow a material into the vapor phase to condense into a thin film
sputtering: see SPT
standard state: the pure form of a substance at 1 bar pressure for any given temperature.
stopband: the primary region of reflection or absorption of a rejection filter.
STP: standard temperature and pressure; corresponds to 0C, 1 atm.
streamline: the path taken by any particle in a steady, laminar flow.
superconductor: A material which has no resistance to electricity. When passing current through a superconductor, there is no loss of electrical power due to these materials.
supercritical liquid: a liquid which exists at temperatures above the normal boiling point; this is brought about through high pressure. Reactivity of solutes in these liquids can be changed drastically with minor changes in temperature and pressure.
superfluid: a fluid that flows without viscosity (ex: He-II)
superhigh surface area carbon: any carbon which has a specific surface area greater than 2630 square meters per gram
superionic materials: Materials which exist largely in the ion phase. These are extremely useful in making conductors which work via ionic migration.
supersaturated vapor: A vapor which will spontaneously begin to condense in the presence of nucleation centers.
surface tension: (gamma); the force F per unit length L that acts across any line in a surface, tending to pull the surface closed.
surfactant: a species that is active between two phases. It accumulates at the interface and changes the surface tension.
syngas: a mixture of gases (largely carbon monoxide and hydrogen) that results from heating coal in the presence of steam. Can be used as a fuel.
TDFS: time-dependent fluorescence shifts
TEM: transmission electron microscopy. What you do is take the sample, grind it up, then place an aqueous suspension of it on a grid where the electron microscope can get at it.
temporal coherence: how much waves stay in step along a beam path
theoretical plates: represents how many times you do a separation in purification; can be used to describe column chromatography, GC, or HPLC.
thermal motion: chaotic, random motion of molecules due to the temperature
thermal neutrons: neutrons that have not been slowed down and have reached equilibrium with matter at room temperature
thermistor: a substance which changes its resistance with temperature. Those developed as infrared detectors are known as bolometers.
thermionic emission: you can get a current to flow from a heated filament to a positive electrode in a vacuum; this emission is simply electrons flowing from the filament to the positive electrode.
thermocouple: two metals are put together side by side when heated, one metal expands more than another due to differences in the coefficients of thermal exansion, and the strip bends. This can be used as a switch, as in a thermostat.
thermogravimetric analysis (TGA): when you heat a sample to observe weight changes; used when studying the loss of waters of hydration or CO2.
thermoplastics: plastics that can be softened by heating and return to their original state on cooling.
thermopneumatic detector: when the radiation incident on a gas in a closed chamber increases the temperature and pressure of a gas, a mirror on the cell wall moves. This movement is measured optically, and can be used to determine the amount of radiation incident on the cell.
thermovoltaic detector: an IR detector where temperature changes of a junction of dissimilar metals because of changes in the level of incident radiation causes a change in voltage.
time dilation: the idea that time travels slower for somebody in a moving reference frame; consequence of relativity.
time-of-flight (TOF): when you apply the same translational energy to all particles; the lighter particles will travel a shorter distance over a charged plate because there is less momentum to carry them forward.
total binding energy: energy required to break a nucleus into its component protons and neutrons
total internal reflection second harmonic generation (TIR SHG): This is what happens when you shine the exitation beam and probe beam on a liquid-liquid surface. What you are counting on happening is that the beams will reflect off of the bottom liquid and give the second harmonic signal you’re looking for.
transducer: a device that turns one kind of energy to another (like a loudspeaker turns electrical energy to sound); a device that converts a light signal into an electrical signal
transient grating techniques: what you do in one of these studies is to get several beams coming into a sample that have different circular polarity. Their interference sets up a diffraction grating which can be used to run experiments.
transistor: a device used to give current and power amplification
transverse relaxation time (T2): the time it takes after a pulse in NMR for the spins to get out of phase with one another. This is also called the spin-spin relaxation time.
transverse wave: when a wave has the property that the particles of the wave move perpindicular to the motion of the wave itself, such as a water wave.
TREPR: time-resolved electron paramagnetic resonance; a way of identifying transient radicals
trichroism: exhibits different colors in 3 different directions when viewed by transmitted light
tungsten filament: an IR light source where the emitter is a tungsten filament; the IR output range is limited by the window material, although the window material may actually heat up enough to serve as a blackbody emitter.
tunneling: the penetration of a particle into a classically-forbidden region.
turbulent flow: when a moving liquid exhibits erratic, whirlpool-like currents.
Turing pattern: patterns that arise from oscillatory coupled cells. AI.
two-dimensional NMR: A method in which you can take NMR peaks that are stuck on top of each other and separate them. The plot has one axis as the normal NMR axis, and the other corresponds to the spectrum when you hit the sample with 90 degree radiation.
Tyndall effect: the scattering of visible light by a colloidal dispersion.
UHV: ultrahigh vacuum
ultrasonic: sound waves that have frequency higher than we can hear (20,000 Hz)
uniphase: a wavefront is uniphase if it has the same phase at all points
unipotential lens: see einzel lens
Vacuum ultraviolet (VUV): UV radiation of high enough frequency that air will absorb it. UHV is ultrahigh vacuum-UV, which is of higher frequency still.
Van der Waals picture of condensed matter: molecular dynamics of dense fluids are determined primarily by the size and shape of molecules; that is, the short-range repulsive internuclear forces.
vector: a quantity that has both direction and magnitude, such as velocity.
velocity selector: used with molecular beams; slotted disks that make sure only particles with the desired speed reach the target.
Venturi tube: a pipe with a narrow constriction; if it has an opening at this constriction, it will tend to pull a vacuum through it equal to the vapor pressure of the liquid; a consequence of Bernoulli’s principle
viscosity: the internal friction of a liquid
visible spectrum: radiation of wavelength 400-750nm.
voltage: equal to the potential difference between two things.
VOM: volt-ohm-meter; a multimeter that measures voltage, current and resistance
Walden reductor: a metal reduction column filled with silver
Walsh diagram: a diagram that shows the variation of orbital energy with molecular geometry
Wedge prism: used for beam steering
Welsbach mantle: a gauze mesh, similar to the one in gas lanterns, impregnated with ThO2 and a small amount of CeO2 which is heated by either a burning gas or electric charge. It gives off IR radiation between 10-100 microns.
X-ray fluorescence spectroscopy (XRF): measures the energies of the inner electrons of an atom by knocking them off with X-rays; good for about 35 elements. Handy because it is not a destructive method of analysis - the electrons are simply elevated to outer orbitals and the relaxation to the inner orbitals is measured.
Young’s modulus (E): the ratio of longitudinal stress to longitudinal strain.
Zeeman effect: this is the effect of overcoming the normal degeneracy of electron spin states by applying a magnetic field which can interact with the magnetic moment of the electron. This is observed when atoms are subjected to a powerful magnetic field resulting in the spectral lines being split into a number of component lines.
zeroth law of thermodyamics: If A is in thermal equilibrium with B and B is in thermal equilibrium with C, then A and C are in thermal equilibrium
ZSM-5 zeolites: Commonly
used zeolites which are extremely good at removing NOx. Used
in auto emissions control and direct composition of NO to N2 and O2.