Molecular Motion and the Moment Analysis of Molecular Spectra in Condensed Phases. I. Dipole‐Allowed Spectra

摘要: Molecular absorption and emission spectra (of a vibrational transition or of single component an electronic transition) are analyzed in terms moments their intensity distributions. The results valid for arbirtary intermolecular potential energy. first‐moment formula allows one to identify, experimental spectrum, the shifted band origin. second moment is found have additive contributions from dynamical fluctuations environmental frequency shift. depend on average molecular rotational kinetic energy, principal inertia molecule, direction relative axes inertia. In classical limit, energy determined by temperature, then independent If general, measurement gives upper limit shift fluctuation effect small, measures third higher averages angular derivatives as well shift‐fluctuation‐type moment. For example, fourth linear molecule mean squared torque molecule.