Calculation of the rotational Raman spectrum of H2 dissolved in water

Abstract

We have carried out molecular dynamics simulations on the system of a hydrogen molecule dissolved in water or in heavy water in an attempt to understand the experimental results of Taylor and Strauss [J. Chem. Phys. 90, 768 (1989)] for the rotational Raman spectrum of H2. By extracting from the simulation the time-varying potential felt by the H2 molecule, we have computed linewidths in various theoretical limits: static, adiabatic, and Redfield. A start has been made at the nonadiabatic calculation. H2/water is a system of a quantum rotor in a classical bath, in which there is little separation of time scales. The calculations do produce the correct absolute magnitude of the linewidths without adjustable parameters. However, the details of the observed variation of the widths with J and with the change of H2O to D2O are not reproduced and are discussed.