Publisher's Synopsis
Photoluminescence is a phenomenon in which a fluorophore absorbs electromagnetic (EM) radiation of a particular energy and re-emit light (photon) of a lower energy. Photoluminescence process is achieved through excitation of fluorophore via. Mechanical, physical or chemical process. Photoluminescence is divided into fluorescence and phosphorescence.
In fluorescence and phosphorescence an electron is excited to an orbit of higher energy and then de-excited to a lower energy orbit by the emission of a photon. In both the cases, the process of emission of photons is different. In fluorescence, emission of photons happens due to deactivation of electron from the lowest vibrational level of first excited state to ground state. The order of the time of absorption is enormously short in
In order to begin fluorescence process, molecules must absorb sufficient energy from EM radiation. If the absorbed energy of light is higher or equal to energy difference between two electronic states it pushes the valence electrons from ground state to higher electronic state. Thus it puts the fluorophore in a higher electronic state.
