Probing molecular dynamics using action, Doppler and photoacoustic spectroscopy

Vibrationally mediated photodissociation involves laser techniques that deposit energy in skeletal motions of molecules, which subsequently interact with photons promoting them to excited electronic states. The molecules adiabatically or non-adiabatically dissociate, releasing atomic photofragments. Action and Doppler spectroscopies, expressing the yield of the ensuing fragments vs. the vibrational excitation and UV probe lasers, respectively, are measured. These spectra together with the simultaneously measured photoacoustic spectra provide a unique means for accessing the dynamics on the ground and excited potential energy surfaces. Experimental studies concerning acetylene and its 1-butyne homologue demonstrate how the mechanism of the chemical transformations and the nature of rovibrationally excited states are highlighted by photolysis of pre-excited molecules. (c) 2004 Elsevier B.V. All rights reserved.