UV Luminance Spectroscopy – Section 1

6. Internal conversion is where

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

Correct Answer: C. A molecule converts excess electronic energy to vibrational energy

7. Why phosphorescence measurements are usually made at a low temperature?

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 decrease the efficiency of the detector

Correct Answer: B. To promote phosphorescence by slowing the rate of radiationless transfer processes

8. Fluorescence occurs when

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

Correct Answer: B. a molecule returns to the electronic ground state from an excited singlet state by losing it’s excess energy as a photon

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