Question

I'm doing a fluorescence experiment in physical chemistry. My question about this is why are there molecules in three ground state levels?

Answer 1

In fluorescence experiment there molecules are in three ground state levels because this process is governed by three important events ( all these processes are on timescales )

- By an incoming photon excitation of a susceptible molecule which happens in femtoseconds (10E-15 seconds),

- The excited state electrons of Vibrational relaxation to the lowest energy level is much more slower which can be measured in picoseconds (10E-12 seconds).

- The final process includes return of the molecule to the ground state & emission of a longer wavelength photon which occurs in long time period of nanoseconds (10E-9 seconds)