Vibrational energy and molecular thermometers in liquids ultrafast IR-raman spectroscopy

In this update to our 2001 article [1,2], we describe advances in instrumentation for IR-Raman spectroscopy and measurements on vibrational energy in molecular liquids. We will emphasize quantitative determination of the efficiency of energy transfer pathways and the use of molecular thermometers [3-9], which, as vibrationally excited molecules lose their excess energy to the bath, can sense the growing levels of bath excitation. The systems that will be discussed in detail are water under extreme conditions, biologically relevant molecules in aqueous solution, where the water itself serves as the thermometer, and benzene and d₆-benzene, where dissolved CCl₄ is the molecular thermometer.