Anomalously Long Radiative Lifetimes of Molecular Excited States

Publisher Website
Google Scholar
Abstract
Certain excited states of molecules have been found to have anomalously long radiative lifetimes compared with the values calculated from integrated absorption coefficients. Using the properties of the stationary states, four mechanisms which may account for such anomalous lifetimes in collision‐free molecules are presented. Although the four mechanisms bear a one‐to‐one relationship to those which have been discussed using semiclassical concepts, certain consequences of the more exact treatment do not appear in the semiclassical approach. In particular, it is shown that the two mechanisms which are most important for polyatomic molecules lead to highly perturbed energy levels and correspondingly complex spectra. The spectra of NO2, SO2, and CS2 are discussed as examples of the proposed mechanisms.