Visualization of multi-dimensional chemical dynamics using crossed molecular beam scattering with ion imaging and variable collision energy

用交叉分子束离子成像法研究了O(1D_2)与甲烷在0.9-6.8千卡/摩尔碰撞能量范围内的反应。根据碰撞能量关系，估算了O(1D_2)与CH_4和CD_4的抽提途径势垒高度分别为0.7±0.3和0.8±0.1千卡/摩尔。与CD_4的插入反应对CD_3的速度分布表现出强烈的角度依赖性，而对CH3的依赖性要小得多。结果表明，尽管在甲醇中间体寿命内的分子内振动重分布(IVR)在两种同分异构体中都是受限的，但在Cd_3OD中发生的IVR相对比CH_3OH更广泛，这可能是由于Cd_3OD的振动态密度较高所致。

The O(1D_2 reaction with methane is studied using a crossed molecular beam ion imaging method at collision energies of 0.9 - 6.8 kcal/mol. From the collision energy dependence, the barrier height for the abstraction pathway is estimated as 0.7±0.3 and 0.8±0.1 kcal/mol for O(1D_2) with CH_4 and CD_4, respectively. While the insertion reaction with CD_4exhibits strong angular dependence of the CD_3 speed distribution, CH3exhibits considerably smaller dependence. The result suggests that, although intramolecular vibrational redistribution (IVR) within the lifetime of the methanol intermediate is restrictive in both isotopomers, relatively more extensive IVR occurs in CD_3OD than CH_3OH, presumably due to the higher vibrational state density.