ROTATIONAL ENERGY TRANSFER IN THE $B^{3}\Pi(0_{+})$ STATES OF IF AND ICI: A SYSTEMATIC STUDY OF STATE-TO-STATE RATE $COEFFICIENTS^{\ast}$

Abstract

$^{\ast}$Supported by Air Force Office of Scientific Research Contract No. F49620-86-C-0061.Author Institution: Physical Sciences Inc.A CV laser induced fluorescence study has been performed to determine rotational to translational (R-T) energy transfer rate coefficients for selected J' levels in the heteronuclear molecules IF and ICl. Steady state populations of specific rovibronic levels were prepared using either an $Ar^{+}$ laser or a ring dye laser. Rate coefficients were determined for state-to-state R-T transfer for a variety of bath gases: $He, Ne, Ar, Kr, Xe, N_{2}$, and $CF_{4}$ and for several initially excited rotational levels. Over 1000 rate coefficients for individual $\Delta J$ changing collisions have been measured. Dramatic differences in the abilities of various collision partners to transfer angular momentum to and from IF and ICI are observed. Comparisons are made to theoretical models that predict the scaling of the rate coefficients as a function of $\Delta J$