Rovibrational energy transfer in the 4nuCH manifold of acetylene, viewed by IR-UV double resonance spectroscopy. 5. Detailed kinetic model

Time-resolved infrared-ultraviolet double resonance (IR-UV DR) spectroscopy provides a distinctive way to examine collision-induced state-to-state energy transfer between rotational J-levels in vibrational manifolds of small polyatomic molecules, such as acetylene (C2H2) in its electronic ground state X. We consider the 4nuCH rovibrational manifold of C2H2 at approximately 12,700 cm(-1), where the principal source of IR-brightness is the (nu1+3nu3) or (1 0 3 0 0)0 Sigma+u vibrational combination level. In this highly congested manifold, anharmonic, l-resonance, and Coriolis couplings affect the J-levels of interest, implicating them in a complicated variety of intramolecular dynamics. Previous papers of this series have reported several seemingly anomalous J-resolved phenomena induced by collisions in C2H2 gas at room temperature with pressures and IR-UV pump-probe delay intervals corresponding to remarkably high Lennard-Jones collisional efficiencies P: odd-DeltaJ rotational energy transfer (10(-3)