Fluorescence and Phosphorescence:

In the emission spectra of atoms and molecules discussed above the energy of the emitted radiation is similar as that used for excitation. Within some atomic and molecular systems the emitted radiation is of variant frequency than that of the excitation radiation.  These are either because of fluorescence or phosphorescence.  Within such emissions, the excited atom or molecule does not emit radiation straight from the excited state. On the other words the excited species relaxes down to excited state of lower energy by non-radiative processes and then from there it comes to the ground state accompanied through the emission of radiation.