Relaxation of Molecules with Chemically Significant Amounts of Vibrational Energy: The Dawn of the Quantum State Resolved Era

Abstract

The simplest model for chemical reactions that proceed by unimolecular decomposition in the gas phase is the Lindemann mechanism, in which a substrate S is excited by collisions to a level S* with energy sufficient to cause bond breaking or molecular rearrangement ( 1-3). For large molecules, the time scale for decomposition of S* is sufficiently long that further collisions with the bath molecules can cause deactivation of the excited substrate, thus quenching the reaction process. The overall mech­ anism can be summarized by the following equations: