An atom is in its excited state. Does the probability of its coming to ground state depend on whether the radiation is already present or not? If yes, does it also depend on the wavelength of the radiation present?

Question

Philoid · Accepted Answer

In case of stimulated emission, atoms come to ground state if there is a stimulated radiation present. In that case, it also depends on the wavelength of radiation. Only a radiation of suitable wavelength can stimulate atoms for emission.

However in case of spontaneous emission, atoms come to the ground state spontaneously. Thus, it does not depend on the presence of radiation or its wavelength.