Chapter 6 Flashcards
The angle of the cone of light exiting a sample observed by microscopy
Angle aperture (AA)
Materials that have more than one refractive index
Anisotropic
Scattering interactions that start from an excited state; a type of inelastic scattering
Anti-Stokes scattering
An opening, often adjustable, that determines how much light or electromagnetic energy passes through; usually designed to limit stray light
Aperture
Ionization using an electrical discharge used for LCMS instrumentation and some IMS instrumentation
Atmospheric pressure chemical ionization (APCI)
Generically, the width of a band of electromagnetic energy measured in terms of wavelength
Bandwidth
In a spectrum, chromatogram, or other peak-based output, the situation that occurs when there is some portion of flat baseline in the space separating the peaks
Baseline resolution
A lens that, when inserted into the optical train of a microscope, allows the viewer to see an image of the filament; used to establish Koehler illumination. A lens that focuses on the rear aperture of the objective lens assembly
Bertrand lens
The difference in the refractive indexes of an anisotropic material; can be calculated by subtraction or with a Michel-Levy chart
Birefringence
Electrophoresis in a capillary tube that exploits electroosmotic flow
Capillary zone electrophoresis/CZE
A focusing device that utilizes highly polished mirrors in lieu of glass lenses
Cassegrain system
A component of mass spectrometers in which collision gases are introduced into a high vacuum region to facilitate collisional dissociation of complexes and compounds
Collision cell
The assembly in a microscope below the sample stage; focuses the beam into a tight cone of light
Condenser/condenser lens
The space between the lens and the image sensor where the image being filmed will appear in focus to the human eye
Depth of focus
A material that has two colors due to different absorbances depending on orientation
Dichroic
An older form of micro-IR in which the diffuse reflections off a sample act as the attenuated IR signal
Diffuse reflection
Natural spreading of a concentrated band of analyte
Diffusion
Physical separation of constituent wavelengths by a device such as a prism or grating
Dispersion
Ionization and fragmentation of molecules entering a mass spectrometer achieved by collision with a stream of electrons produced by a heated filament
Electron impact ionization/quadrupole mass filter
Transition of an atom or ion from the ground to an excited state via electron promotion among atomic orbitals
Electronic transition
Flow of ions that occurs in a silica capillary tube exploited in capillary electrophoresis
Electroosmotic flow
Separation of charged and neutral species based on size-to-charge ratio
Electrophoresis
An ionization source for LC/MS that applies charge to solvent droplets that evaporate and eventually disperse via Coulombic explosion
Electrospray ionization (ESI)
In an ATR, a series of reflective adsorptive interactions; multiple internal reflections
Evanescent wave
A sample preparation technique that removes the analyte from the matrix
Extinction
The lens or lens assembly closest to the sample in optical microscopes
Eyepiece
How large a portion of the sample can be seen in focus at one time
Field of view
A GC detector selective to organic carbon and C-H bonds; based on creation of charged species in the flame
Flame ionization detector (FID)
A cell used to isolate separated analytes in a flowing system long enough to obtain a spectrochemical measurement with an adequate pathlength
Flow cell
The distance along the optic axis of a lens to the principal focus
Focal length
A combination of a separation module with a detector module such as GC-MS (GCMS); hyphen is often omitted
Hyphenated instrument
An extremely hot excitation source for elemental analysis via emission or mass spectrometry. A plasma is not a flame and reaches much higher temperatures, so it can excite a significant portion of the ground state atoms. The plasma is created in the torch portion of the inlet
Inductively coupled plasma (ICP) torch
A plot of the distance traveled in an interferometer by the mirror versus intensity; can also be plotted versus time
Interferogram
Techniques that exploit interference (constructive and destructive) to limit or control the wavelengths of light transmitted from a source to a detector
Interferometry
Gas phase separation of ion/molecule clusters at atmospheric pressure; generically gas phase electrophoresis
Ion mobility spectrometry
In mass spectrometry, a substance that has the same molecular weight or atomic weight of the substance of interest
Isobaric interference
Materials that have the same refractive index regardless of orientation
Isotropic
A method of filtering ions in a collision cell such as an ICP-MS or LC-MSn instruments
Kinetic energy discrimination (KED)
In a microscope, the alignment of lamp and lenses that produces optimal and even illumination
Koehler illumination
A detector that ionizes and fragments molecules and creates a reproducible and usually unique fragmentation pattern that can be used for identification
Mass spectrometer (MS)
The process of a solute moving in and out of stationary phase
Mass transfer
Capillary electrophoresis using micelles and selective partitioning to separate neutral species
Micellar electrokinetic chromatography (MEKC)
Structures formed by surfactants above a critical concentration in water
Micelles
Use of a microscope in conjunction with a spectrometer
Microspectrophotometry
Output of an ion mobility spectrometry
Mobility spectrum
A device such as a prism, filter, or grating that selectively removes all but a narrow range of electromagnetic energy from an impinging source
Monochromator
A sample introduction device used with ICP-MS and other techniques; creates a fine mist for introduction into the instrument
Nebulizer
A GC detector selective to N- and P-containing compounds; similar in design to an FID and includes and alkali salt
Nitrogen-phosphorus detector (NPD)
An ability of a lens to collect light
Numerical aperture (NA)
The lens or lens assembly closest to the sample in optical microscopes
Objective lens
The lens or lens assembly closest to the viewer’s eyes in optical microscopes
Ocular lens
Light path that doesn’t follow the principle optical axis; set off at an angle
Off-axis
The imaginary line that runs through the point of a curved lens where the curvature is at a maximum; may or may not be the geometric centerline
Optic axis
A compound used to standardize the performance of mass spectrometers to insure intercomparability of spectra
Per-Fluorotributylamine (PFTBA)
A detector that works by detecting photons dispersed in space; one photodiode per geometrical location
Photodiode array (PDA)
A material that has two or more colors due to different absorbances depending on orientation
Pleochroism
Chemical bonds that are altered by passage of light; bonds in which the electron clouds can be distorted by scattering interactions
Polarizable bonds
Light that vibrates in a single plane
Polarized light
A technique that uses polarizing filters in the optical train of a microscope
Polarized light microscopy (PLM)
The point in space where light rays that have passed through a lens will converge
Principal focus
A material such as a synthetic fiber that is ordered but not crystalline in the sense that a solid inorganic material is
Pseudocrystalline
A transition of an excited state to a lower state that occurs without emission of a photon; a transition in which energy is dissipated typically as heat
Radiationless transition
A vibration technique based on scattering and polarizable bonds
Raman spectroscopy
Scattering that results in no change in wavelength; elastic scattering
Rayleigh scattering
A component of mass spectrometers in which collision gases are introduced into a high vacuum region to facilitate collisional dissociation of complexes and compounds
Reaction cell
An image created by a lens that can be projected onto a screen; an image that exists at a plane in space and doesn’t require one to look through a lens to see it
Real image
The ability of a lens or optical train to distinguish two objects, = 0.6/NA
Resolving power
An expression of the slowing of light as it propagates along and perpendicular to the optic axis of the material. The greater the difference in speed, the greater the retardation
Retardation
In polarizing light microscopy, the distance (in nm) that separates the emerging perpendicular and parallel rays emerging from a birefringent sample
Retardation distance
An imaging technique that uses interaction of a sample with electrons to create an image
Scanning electron microscope (SEM)
An expression that described the angles of refraction of light when it passes through an interface; (sin(i))/(sin(r)) = n2/n1
Snell’s law
“Perfect reflection”; angle of reflection = angle of incidence; occurs at a surface where there is a change in the refractive index
Specular reflection
Scattering interactions that start from the ground state; a type of inelastic scattering
Stokes scattering
A process where energy is absorbed to some degree by a substrate before being reflected
Surface absorption-reflection (SAR)
A series of mass filters placed in tandem (in space or time) such as a triple quadrupole mass spectrometer
Tandem mass spectrometry
A measure of the efficiency and resolving power of a chromatographic column; based on distillation model
Theoretical plates
A device that converts whatever arrives at a detector (photons, ions, etc.) into an electrical signal
Transducer
A plot of HETP versus flow rate; describes three contributing factors to band broadening and thus column efficiency
van Deemter curve
An image created by a lens that doesn’t exist in a point in space and one that can’t be captured on a screen. It exists only when viewed through the lens
Virtual image
The amount of space available between the stage and the lens of a microscope for sample insertion
Working distance
A technique in which electrons analogous to light where the diffraction pattern relates to crystal structure
X-ray diffraction (XRD)
