Intramolecular Vibrational Energy Redistribution and Intermolecular Energy Dissipation of Polyatomic Molecules in Liquids

In small molecules the lifetime of vibrational modes critically depends upon the energy states and the anharmonic coupling of the individual molecule. Large molecules in the statistical limit exhibit very rapid intramolecular energy redistribution (≤ 1 ps). Evidence is presented for the redistribution of vibrational energy over the Vibrational manifold of the electronic ground state. A temporary internal temperature may be assigned to the excited molecules. Intermolecular energy dissipation occurs slowlier. A time constant of approximately 10 ps is observed when probed approximately 3000 cm⁻¹ above the ground state.