Spectroscopic Method Flashcards
Study of the interaction of electromagnetic radiation and matter.
Spectroscopy
Method when a photon is absorbed by an atom or molecule which undergoes transition from lower energy stateto higher energy state
Absorption spectroscopy
Occurs when an atom or molecule in an excited state returns to a lower energy state, and the excess energy is often released as photon
Emission spectroscopy
Emission following the absorption of a photon is called ____
Photoluminescence
Emission following a chemical reaction is called
Chemiluminescence
Choose the correct order of spectroscopic instrumentation.
A. Source, wavelength selector, sample container, detector, readout
B. Detector, source, wavelength selector, sample container, readout
C. Readout, detector, sample container, wavelength selector, source
A
Source of radiation in spectroscopic methods can either be ____ or _____ sources
Continuum kr line sources
Source of radiation in spectroscopic methods can either be ____ or _____ sources
Continuum or line sources
Lamp that emits radiation over a broad range of wavelengths, with a relatively smooth variation in intensity
Continuum sources
Lamp that emits radiation at selected wavelengths
Line sources
Highly useful line sirce because of their high intensities, narrow bandwidth, abd coherent nature of outputs
Laser (light amplification by stimulated emission of radiation)
Uses either absorption or constructive and destructive interference to control the range of selected wavelengths
Filter
Since filter can’t perform continuous selection of wavelengths,____ is used.
Monochromator
Sample container in spectroscopic methods that’s made of quartz, glass, and silica
Cuvette or cells
A device that identifies, records, or indicates a change in one of the variables in it’s environment
Detector
Converts various type of chemical and physical quantities into electrical signals
Transducers
Transducers used for detecting UV/Vis radiation. About 10^6 to 10^7 electrons are produced at the anode for each photon that strikes it’s photocathode
Photomultiplier tube (PMT)
Device that displays the signal from the transducer in a form that is easily interpreted.
Signal Processor
Radiation from the instrument that is outside the the nominal wavelength band chosen for the determination
Stray light
When a molecule absorbs EMR, the number of photons passing through the sample decreases. Measurement of this decrease is called
Absorbance
Plot of absorbance as function of the photon’s energy is ____
Absorbance spectrum
Ratio of the radiant power passing through a sample to that from the source
Transmittance
More commonly used in expressing attenuation of radiation because it is a linear function of analytes concentration
Absorbance
Simplest instrument in UV-VIS that uses a single optical path between source and detector
Filter photometer
Instrument equipped with a fixed- wavelength monochromator
Single Beam spectrophotometer
Instrument equipped with a scanning monochromator that allows for automated recording of spectra. More versatile than S-BS
Double beam spectrophotometer
In this instrument, radiation passes through the sample and is dispersed by grating
Diode array spectrometer
First step in all atomic spectroscopic procedures is _____, a process in which a sample is converted into gas-phase atoms or elementary ions
Atomization
With this atomizer, samples are introduced in a steady, continuous stream.
Continuous atomizer
With this atomizer, individual samples are injected by a syringe or autosampler
Discrete atomizer
With this atomizer, individual samples are injected by a syringe or autosampler
Discrete atomizer
Widely used for analysis of trace metals in a variety of sample matrices
Atomic Absorption Spectroscopy (flame)
Ideally suited for a multi -elemental analysis because all analytes in a sample are excited simultaneously
Atomic emission spectroscopy
Common light source for atomic measurements is __
Hollow cathode lamp
Anion- tungsten
Cation- Ne or Ar
Hollow cathod lamp is a ___ lamp that permits determination of more than one element
Multi element
AAS Instrumentation
Nebulization
Desolation
Volatilization
Dissociation
Ionization
Differentiate AAS and AES
AAS
Flame
Furnace
AES
Plasma ES
ICP-MS
Electrically conducting gaseous mixture present in AES containing significant concentration of cations and electrons
Plasma
