13. Which of the following is true: A. Fluorescence is always blue-shifted compa

Question

13. Which of the following is true: A. Fluorescence is always blue-shifted compared to absorption B. The quantum yield of fluorescence measures the fraction of transitions that occur by fluorescence C. Transitions from excited states arise only from nonradiative decays. R. The cebserved raite of decay of an excited state is always slower than the rate due to fluorescence 14. The linewidth of an optical band in a protein shows B. the energy of the excited states C. the switching time between conformations D. the distribution of vibrational energies 15. The Franck-Condon principal states A. the frequency of an optical band is related to the energy levels of electrons B. optical bands involve transitions of electronic states C. transitions have no changes in nuclear coordinates D. all of the above

Explanation / Answer

13. Answer : B

A. Flourocence has always longer wavelengh hence it is false

B.is defined as the ratio of the number of photons emitted to the number of photons absorbed.(i.e. fraction of transition occurs by flourocence.

Transition from excited state is always radiative decay.

D.in correct

14. Answer : D

A.line witdth is not related to pigment

B.energy state is not related to line width

C.not related to conformation of proteins

D. Correct answer

15. Answer : D

The Franck–Condon principle is a rule in spectroscopy and quantum chemistry that explains the intensity of vibronic transitions. Vibronic transitions are the simultaneous changes in electronic and vibrational energy levels of a molecule due to the absorption or emission of a photon of the appropriate energy.

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