UV Luminance Spectroscopy problems
- 1. What is the relationship between wavelength and wave number?
Options- A. Wavenumber = 1 / wavelength in centimeters
- B. Wavenumber - wavelength in nanometers = 1
- C. Wavelength in nanometers x wavenumber = 1
- D. None of the above Discuss
Correct Answer: Wavenumber = 1 / wavelength in centimeters
- 2. Why must the radiation source for fluorescence spectrometry be more powerful than for absorption spectroscopy?
Options- A. Because the magnitude of the output signal is proportional to the power of the incident radiation
- B. Because the sample won't fluoresce if the incident radiation is of low power
- C. To allow for scattering by the sample
- D. None of the above Discuss
Correct Answer: Because the magnitude of the output signal is proportional to the power of the incident radiation
- 3. Why phosphorescence measurements are usually made at a low temperature?
Options- A. To prevent thermal degradation of the phosphorescent species
- B. To promote phosphorescence by slowing the rate of radiationless transfer processes
- C. To increase the efficiency of the detector
- D. To decease the efficiency of detector Discuss
Correct Answer: To promote phosphorescence by slowing the rate of radiationless transfer processes
- 4. In the intersystem crossing
Options- A. the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
- B. a molecule converts its excess energy to light, and emits a photon
- C. a molecule converts excess electronic energy to vibrational energy
- D. all of the above Discuss
Correct Answer: the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
- 5. For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule?
Options- A. Because a change in dipole moment lowers the energy required for electronic transitions
- B. Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment
- C. Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching
- D. All of the above Discuss
Correct Answer: Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment
- 6. Why do fluorescence spectrometers often use double-beam optics?
Options- A. So a reference solution can be used
- B. To compensate for beam attenuation by the monochromator
- C. To compensate for power fluctuations in the radiation source
- D. All of the above Discuss
Correct Answer: To compensate for power fluctuations in the radiation source
- 7. Fluorescence occurs when
Options- A. a molecule returns to the electronic ground state from an excited triplet state by losing it's excess energy as a photon
- B. a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon
- C. a molecule lowers its vibrational energy by losing it's excess energy as a photon
- D. none of the above Discuss
Correct Answer: a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon
- 8. Internal conversion is where
Options- A. the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
- B. A molecule converts its excess energy to light, and emits a photon
- C. A molecule converts excess electronic energy to vibrational energy
- D. none of the above Discuss
Correct Answer: A molecule converts excess electronic energy to vibrational energy
More in Biochemistry:
Programming
Copyright ©CuriousTab. All rights reserved.