An investigation of nonadiabatic interactions in Cl(2Pj)+D2 via crossed-molecular-beam scattering.

We have determined limits on the cross section for both electronically nonadiabatic excitation and quenching in the Cl(2Pj)+D2 system. Our experiment incorporates crossed-molecular-beam scattering with state-selective Cl(2P1/2,3/2) detection and velocity-mapped ion imaging. By colliding atomic chlorine with D2, we address the propensity for collisions that result in a change of the spin-orbit level of atomic chlorine either through electronically nonadiabatic spin-orbit excitation Cl(2P3/2)+D2→Cl*(2P1/2)+D2 or through electronically nonadiabatic spin-orbit quenching Cl*(2P1/2)+D2→Cl(2P3/2)+D2. In the first part of this report, we estimate an upper limit for the electronically nonadiabatic spin-orbit excitation cross section at a collision energy of 5.3 kcal/mol, which lies above the energy of the reaction barrier (4.9 kcal/mol). Our analysis and simulation of the experimental data determine an upper limit for the excitation cross section as σNA≤0.012 Å2. In the second part of this paper we investigate the propensity for electronically nonadiabatic spin-orbit quenching of Cl* following a collision with D2 or He. We perform these experiments at collision energies above and below the energy of the reaction barrier. By comparing the amount of scattered Cl* in our images to the amount of Cl* lost from the atomic beam we obtain the maximum cross section for electronically nonadiabatic quenching as σNA≤15-15+44 Å2 for a collision energy of 7.6 kcal/mol. Our experiments show the probability for electronically nonadiabatic quenching in Cl*+D2 to be indistinguishable to that for the kinematically identical system of Cl*+He. [ABSTRACT FROM AUTHOR]