Intramolecular distributions. I: Theory

In this paper, a theory of intramolecular distributions for polyatomic molecules is presented. This approach has been found to be of great value in calculating radiative and nonradiative transitions. The intramolecular distributions (ID) are introduced by the aid of generating functions which incorporate typical molecular effects such as electronic origin and force constant shifts, and mode mixing. For some special cases, the main properties of multidimensional intramolecular distributions, which involve the effect of the density of final and initial states, are formulated in terms of an addition theorem; further use of these distributions in problems of molecular spectroscopy is discussed. Finally, the symmetry behavior of the ID’s is derived and its significance in establishing general relations and correlations between transitions in absorption and emission is discussed.