title: Direct determination of state-to-state rotational energy transfer rate constants via a Raman-Raman double resonance technique: ortho-acetylene in v(2)=1 at 155 K.
abstract: A new technique for the direct determination of state-to-state rotational energy transfer rate constants in the gas phase is presented. It is based on two sequential stimulated Raman processes: the first one prepares the sample in a single rotational state of an excited vibrational level, and the second one, using the high resolution quasi-continuous stimulated Raman-loss technique, monitors the transfer of population to other rotational states of the same vibrational level as a function of the delay between the pump and the probe stages. The technique is applied to the odd-J rotational states of v(2)=1 acetylene at 155 K. The experimental layout, data acquisition, retrieval procedures, and numerical treatment are described. The quantity and quality of the data are high enough to allow a direct determination of the state-to-state rate constant matrix from a fit of the experimental data, with the only conditions of detailed balance and of a closed number of states. The matrix obtained from this direct fit is also compared with those obtained using some common fitting and scaling laws.
authors.affiliation: Instituto de Estructura de la Materia (CSIC), Serrano 123, E-28006 Madrid, Spain. jl.domenech@iem.cfmac.csic.es
authors.forename: José L
authors.initials: JL
authors.lastname: Doménech
authors.forename: Raúl Z
authors.initials: RZ
authors.lastname: Martínez
authors.forename: Angel
authors.initials: A
authors.lastname: Ramos
authors.forename: Dionisio
authors.initials: D
authors.lastname: Bermejo
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D000465:Algorithms; D004735:Energy Transfer; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation / Q000379:methods*; D012399:Rotation; D013696:Temperature
chemical_list: D000114:Acetylene