1|Page
UF PHA6936 FINAL EXAM PREP QUESTIONS
WITH SOLUTIONS
Three Major Components of Fourier Transform Infrared-correct-answer-source of
radiation, a interferometer and a detector
Fourier Transform Infrared Analysis (FTIR)-correct-answer-radiation travels from
the source to the beam splitter where half the radiation is reflected onto the fixed
mirror, the other half reflected to the moving mirror. The beams are then reflected
back towards the beam splitter where half of the recombined beams are
transmitted to the detector while the other half is reflected back to the source,
the detector an interferogram is formed
Advantages of FTIR-correct-answer-quick data collection
all frequencies detected simultaneously
scan sample 10 times per second
increased sensitivity
increased spectral resolution
enhanced data manipulation
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Sample Prep for FTIR-correct-answer-liquids in a sample cell, solids as thin films or
dispersions or powder, mulls or alkali halide disks
Sample Prep when using Microscopy onFTIR-correct-answer-pure compound can
be crushed onto a KBr disk
Types of FTIR Detectors-correct-answer-thermal and quantum
Thermal FTIR Detectors-correct-answer-sense a change in temperature of the
absorbing material
deuterated triglycine sulfate (DTGS) detector
Quantum FTIR Detectors-correct-answer-depend on the interactions of raidation
with electrons in a solid causing electrons to be excited to a higher energy state
mercury cadmium tellurium (MCT)
Infrared Sources-correct-answer-silicon carbide Globar or nichrome coil
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Gas Chromatography (GC)-correct-answer-form of partition chromatography
utilizing a gas mobile phase and liquid stationary phase attached to a fused-silica
column, compounds that prefer the stationary phase will have a longer retention
time than one that prefers the gas mobile phase
Advantages of Attenuated Total Reflection (ATR)-correct-answer-simple, rapid,
non-destructive, less than a milligram of sample used, solid and liquids
ATR-FTIR-correct-answer-sample placed directly on an IR transparent crystal with
a high RI, IR radiation enters the crystal at a specific angle, crystal acts as a prism
causes internal reflectance. An evanescent wave is created and protrudes into the
sample, the sample absorbs energy and the evanescent wave will be
altered/attenuated, the attenuated portion of the wave continues to the detector
creating the spectrum
Angle of Incidence (ATR-FTIR)-correct-answer-amount of radiation that is
reflected and determines depth of penetration
Factors affecting depth of penetration (ATR)-correct-answer-wavenumber of the
radiation, RI of the crystal, angle of incidence, ratio of RIs between the sample and
crystal
, 4|Page
Raman Spectroscopy-correct-answer-monochromatic lasers impinges on the
sample, the incident light interacts with the molecule exciting it causing it to emit
photons and causing light to scatter. Which is then measure depending on the
type
Types of light scatting-correct-answer-elastic and inelastic
Raleigh Scattering-correct-answer-elastic scattering, no change in energy, the
resultant frequency of scattered light is the same as the incident light frequency
Raman Scattering-correct-answer-inelastic scattering, scattered light has energy
changes
Types of Raman Scattering-correct-answer-Stokes and anti-Stokes scattering
Stokes scattering-correct-answer-emitted photons end up at a higher vibrational
energy state or wavelength then the original
anti-Stokes scattering-correct-answer-photons can end up at a lower energy state
UF PHA6936 FINAL EXAM PREP QUESTIONS
WITH SOLUTIONS
Three Major Components of Fourier Transform Infrared-correct-answer-source of
radiation, a interferometer and a detector
Fourier Transform Infrared Analysis (FTIR)-correct-answer-radiation travels from
the source to the beam splitter where half the radiation is reflected onto the fixed
mirror, the other half reflected to the moving mirror. The beams are then reflected
back towards the beam splitter where half of the recombined beams are
transmitted to the detector while the other half is reflected back to the source,
the detector an interferogram is formed
Advantages of FTIR-correct-answer-quick data collection
all frequencies detected simultaneously
scan sample 10 times per second
increased sensitivity
increased spectral resolution
enhanced data manipulation
,2|Page
Sample Prep for FTIR-correct-answer-liquids in a sample cell, solids as thin films or
dispersions or powder, mulls or alkali halide disks
Sample Prep when using Microscopy onFTIR-correct-answer-pure compound can
be crushed onto a KBr disk
Types of FTIR Detectors-correct-answer-thermal and quantum
Thermal FTIR Detectors-correct-answer-sense a change in temperature of the
absorbing material
deuterated triglycine sulfate (DTGS) detector
Quantum FTIR Detectors-correct-answer-depend on the interactions of raidation
with electrons in a solid causing electrons to be excited to a higher energy state
mercury cadmium tellurium (MCT)
Infrared Sources-correct-answer-silicon carbide Globar or nichrome coil
,3|Page
Gas Chromatography (GC)-correct-answer-form of partition chromatography
utilizing a gas mobile phase and liquid stationary phase attached to a fused-silica
column, compounds that prefer the stationary phase will have a longer retention
time than one that prefers the gas mobile phase
Advantages of Attenuated Total Reflection (ATR)-correct-answer-simple, rapid,
non-destructive, less than a milligram of sample used, solid and liquids
ATR-FTIR-correct-answer-sample placed directly on an IR transparent crystal with
a high RI, IR radiation enters the crystal at a specific angle, crystal acts as a prism
causes internal reflectance. An evanescent wave is created and protrudes into the
sample, the sample absorbs energy and the evanescent wave will be
altered/attenuated, the attenuated portion of the wave continues to the detector
creating the spectrum
Angle of Incidence (ATR-FTIR)-correct-answer-amount of radiation that is
reflected and determines depth of penetration
Factors affecting depth of penetration (ATR)-correct-answer-wavenumber of the
radiation, RI of the crystal, angle of incidence, ratio of RIs between the sample and
crystal
, 4|Page
Raman Spectroscopy-correct-answer-monochromatic lasers impinges on the
sample, the incident light interacts with the molecule exciting it causing it to emit
photons and causing light to scatter. Which is then measure depending on the
type
Types of light scatting-correct-answer-elastic and inelastic
Raleigh Scattering-correct-answer-elastic scattering, no change in energy, the
resultant frequency of scattered light is the same as the incident light frequency
Raman Scattering-correct-answer-inelastic scattering, scattered light has energy
changes
Types of Raman Scattering-correct-answer-Stokes and anti-Stokes scattering
Stokes scattering-correct-answer-emitted photons end up at a higher vibrational
energy state or wavelength then the original
anti-Stokes scattering-correct-answer-photons can end up at a lower energy state
