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1)Consider the following statements regarding the processes of fluorescence and

ID: 717289 • Letter: 1

Question

1)Consider the following statements regarding the processes of fluorescence and phosphorescence. Determine whether each statement is true for fluorescence only, true for phosphorescence only, true for both processes, or true for neither process.

a) Energy of absorbed photon equals energy of emitted photon.
b) Photon absorption usually occurs when a molecule is in an excited triplet electronic state.
c) The lifetime of the excited vibrational states is about a femtosecond; the lifetime of the excited electronic state is generally longer than a nanosecond.
d) Vibrational relaxation is a radiative process.

Explanation / Answer

1) Statements regarding fluorescence and phosphorescence

True for fluorescence
c) the lifetime of the excited vibrational state is about a femtosecond; the lifetime of the excited electronic state is generally larger longer than a nanosecond.

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True for phosphorescence

b) Photon absorption usually occurs when a molecule is in an excited triplet electronic state.

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True for both fluorescence and phosphorescence

d) Vibrational relaxation is a radiative process.

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True for neither fluorescence and phosphorescence
a) energy of absorbed photon equals energy of emitted photon.