Ultrafast vibrational energy transfer in the real world: Laser ablation, energetic solids, and hemeproteins

A wide variety of chemical and physical processes that occur in solids produce vibrationally hot (excited) molecules. Recent progress in the theory and experimental measurement of vibrational relaxation and vibrational cooling (VC) in solids is summarized in this paper. Here vibrational relaxation refers to the loss of excitation of the initially prepared state, while VC refers to the return of the hot molecule to its cold ground state. VC is accomplished by energy transfer between the hot molecule and the phonons of the surrounding solid matrix. Both processes occur on the ultrafast time scale in materials that are composed of large molecules. Some real-world applications of VC are discussed. These are processes in which VC plays an important role, including laser ablation and optical damage of polymers, shock-induced chemistry of energetic solids, and hemeprotein photolysis and cooling.