Double resonance vibrational overtone spectroscopy of CF 3 H in a supersonic free jet

Abstract

A recently developed implementation of photofragment spectroscopy, based on specific properties of infrared multiphoton dissociation, has been applied for overtone spectroscopy of the CH stretch vibration in CF<SUB>3</SUB>H. The selectivity and sensitivity of this detection technique, called infrared laser assisted photofragment spectroscopy (IRLAPS), is high enough to combine it with both cooling in a supersonic expansion and infrared-near infrared double resonance excitation. This combination allows one to perform spectroscopy of high vibrational overtones of polyatomic molecules prepared in single J rotational states. The resulting simplification of the overtone spectra of the 4<SUB>2</SUB> vibrational level in CF<SUB>3</SUB>H provides a more accurate estimation of a timescale of intramolecular vibrational energy redistribution from CH chromophore group to the rest of the molecule.