Relaxation of the C-H stretching fundamental vibrations of CHI3, CH2I2, and CH3I in solution

Transient electronic absorption spectroscopy monitors the population of intermediate states in the vibrational energy relaxation of the iodo-substituted methanes, CHI3, CH2I2, and CH3I in solution after excitation of the fundamental C-H stretching vibration. These experiments give times for both intra- and intermolecular energy flow for each molecule. The trend in intramolecular vibrational energy redistribution (IVR) times shows that the local vibrational state structure around the initially prepared states in each molecule, not the overall state density, controls IVR. A comparison of experiments in the solvents chloroform and acetone reveals the solvent role in IVR and shows a strong solvent effect on the intermolecular energy transfer. (C) 2002 American Institute of Physics.