Intramolecular Vibrational Redistribution on the Nanosecond Time Scale: v1and 2v1Spectra of Substituted Acetylene Compounds

摘要: Intramolecular vibrational energy redistribution (IVR) continues to be a subject of wide interest chemical physics. Most previous work has found that NR is rapid (on the time scale 10 psec or less) whenever density ro-vibrational states on order 100 per wavenumber greater. We have been studying IVR in series substituted acetylene compounds using optothermal detection acetylenic C-H stretch its first overtone absorption spectrum cold (few degrees K), collimated molecular beam. This gives resolution MHz, which allows us study times scales up 30 nsec. Our results show these molecules undergo statistical (energy spreads over all modes) but with lifetimes 200 clearly long enough allow bimolecular collisions before reactions, and thus possible mode specific chemistry even gas phase at modest pressure. Chemical modification allowing make interesting correlations between structure relaxation lifetime.