Dynamics of weak and strong collisions: highly vibrationally excited pyrazine (E = 37900 cm(-1)) with DCl

J Phys Chem A. 2008 Oct 2;112(39):9396-404. doi: 10.1021/jp802421f. Epub 2008 Aug 27.

Abstract

The outcome of energy transfer due to single collisions between highly vibrationally excited pyrazine (E = 37,900 cm(-1)) and DCl is measured for the appearance of individual low-J rotational states of DCl using high-resolution transient IR absorption. Appearance profiles from double-Gaussian transient lineshapes were measured for a number of DCl states with J = 2-12. These data give information on the recoil velocity distributions, appearance rates, and populations of individual states of the scattered molecules. These data complement previous studies on high-J state DCl scattering (Li, Z.; Korobkova, E.; Werner, K.; Shum, L.; Mullin, A. S. J. Chem. Phys. 2005, 123, 174306), and together, they provide a full description of the V-RT collisions with DCl that quench pyrazine(E). Scattered DCl (v = 0) molecules with J = 2-21 are rotationally hot with T(rot) = 880 +/- 100 K. Center-of-mass translational energy distributions are T(rel) approximately 700 K for J < 15. Broader velocity distributions are observed for the J = 15-20 states. The rate constant for V-RT energy transfer is 4.6 x 10(-10) cm(3) molecule(-1) s(-1). This value is a lower limit to the overall rate constant for energy transfer and corresponds to approximately 85% of the Lennard-Jones collision rate. We estimate scattering into the DCl (v = 1) state occurs in approximately 1% of collisions. The energy transfer probability distribution P(DeltaE) is presented and yields DeltaE = 888 cm(-1).