Slow intramolecular vibrational redistribution: the latest results for trifluoropropyne, a comparison with the other terminal acetylenes and the mechanism*

摘要: We studied the dynamics of intramolecular vibrational redistribution (IVR) from initially excited mode ν1≈3330 cm−1 (acetylene-type H–C bond) in molecules gaseous phase by means time-resolved anti-Stokes spontaneous Raman scattering. The time constant this process was estimated as 2.3 ns—this is slowest IVR reported so far for room-temperature gases. have compared result with earlier results on other terminal acetylene molecules, and give an explanation low rate. Our suggestion it follows assumption that most probable doorway state leading to bath all vibrational–rotational states consists one quantum stretch two quanta bend, matter energy defect Fermi resonance essentially larger trifluoropropyne than similar molecules. In addition, we obtained rate collision-induced experiments various gas pressures shown observed agreement a theoretical model assuming strong mixing.