Experimental picosecond transient spectra and molecular dynamics for I2 photodissociation

Abstract

Picosecond transient electronic absorption spectroscopy is used to investigate the molecular dynamics of I2 reaction in solution as a function of solvent, pump wavelength and probe wavelength. Our aim is to provide a sufficiently detailed set of experimental observations so that theoretical treatments of the molecular dynamics of a solution reaction can be rigorously tested. The observed transient electronic absorption response times show a strong dependence on probe wavelength, and on the presence of vibrational modes of the solvent in the range 0 to 213 cm−1 but show no dependence on the pump wavelength. These results indicate that the characteristic response times are not due to recombination times, but are more likely due to the time for vibrational or perhaps electronic decay of already recombined molecules.Picosecond transient electronic absorption spectroscopy is used to investigate the molecular dynamics of I2 reaction in solution as a function of solvent, pump wavelength and probe wavelength. Our aim is to provide a sufficiently detailed set of experimental observations so that theoretical treatments of the molecular dynamics of a solution reaction can be rigorously tested. The observed transient electronic absorption response times show a strong dependence on probe wavelength, and on the presence of vibrational modes of the solvent in the range 0 to 213 cm−1 but show no dependence on the pump wavelength. These results indicate that the characteristic response times are not due to recombination times, but are more likely due to the time for vibrational or perhaps electronic decay of already recombined molecules.