| Detailed studies of rovibronic state to rovibronic state reaction dynamics in the gas phase are performed using laser techniques.; A comparative study of Ca or Sr reacting with rovibrationally selected HF or DF has been carried out under single-collision conditions. A thermal beam of Ca or Sr atoms interact with a low-pressure gas of HF(DF) molecules prepared in a selected rovibronic state by a tunable infrared laser (optical parametric oscillator (OPO)). The resulting CaF or SrF products are detected in a quantum-state-specific manner with a tunable visible dye laser using laser-induced fluorescence (LIF). While the Ca + HF(DF) {dollar}to{dollar} CaF + H(D) reaction is well described by a statistical internal energy distribution, the Sr + HF(DF) {dollar}to{dollar} Sr + H(D) system exhibits notable deviation from statistical behavior. The findings for Ca + HF(DF) {dollar}to{dollar} CaF + H(D) are consistent with a model in which the Ca atom inserts into the HF bond to form a long-lived H-Ca-F intermediate. In contrast, the findings for Sr + HF(DF) are interpreted as resulting from the competition between a direct reaction and an indirect reaction that samples the deep H-Sr-F potential well.; The reaction O({dollar}sp3{dollar}P) + HCl (v = 2, J) {dollar}to{dollar} OH (v{dollar}spprime{dollar} = 0, 1; N{dollar}spprime{dollar}) + Cl({dollar}sp2{dollar}P) is studied under single-collision static gas conditions. The O({dollar}sp3{dollar}P) atoms are produced by direct photolysis of NO{dollar}sb2{dollar}. The HCl reagents are prepared in individual rovibrational states (v = 2, J = 1, 6 or 9) with an OPO. LIF is employed to detect the nascent rovibrational state distributions of the OH product. The measured OH state distributions display a pronounced vibrational inversion. The substantial OH rotational excitation observed implies a bent transition state, which is consistent with the prediction of an ab initio surface calculation. While the initial rotational energy of the HCl reagents is systematically increased by roughly 1000 cm{dollar}sp{lcub}-1{rcub}{dollar}, the average fraction of total available energy appearing as OH vibration and rotation remain almost constant. This is in contradiction to the behavior suggested by the kinematic constraints, namely, rotational excitation of the reagents should lead to rotational excitation of the products. For the OH v{dollar}spprime{dollar} = 0 rotational distribution, an anomalous minimum is observed at N{dollar}spprime{dollar} = 10. This behavior might be an evidence for a quantum mechanical resonance in the reactive scattering process. |
