Question

Fluorescence is: (spin refers to spin before and after the transition)

Select one:
a. the emission of a photon during a transition between states with the same spin, S1 --> S0.
b. None of these answers defines fluorescence.
c. a nonradiative transition between states with different spin, T1 --> S0
d. the emission of a photon during a transition between states with different spin, T1 -->S0
e. a nonradiative transition between states with the same spin, S1 --> S0.

Answer 1

the emission of a photon during a transition between states with the same spin, S1 --> S0.

Step-by-step explanation:

Fluorescence refers to a transition in which the electron does not change its spin. It is usually short lived (<10-5s) and emits photons.

Fluorescence differs from phosphorescence in which there is a change of spin and the timescale for phosphorescence is longer than the time scale for fluorescence.

Both fluorescence and phosphorescence occur at shorter wavelengths than the excitation radiation.