An experimental and ab initio reinvestigation of the Lyman-α photodissociation of H2S and D2S
An experimental and ab initio reinvestigation of the Lyman-α photodissociation of H2S and D2S
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DOI：
10.1063/1.1334617
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发表时间：
2001-01-22
影响因子：
4.4
通讯作者：
Ashfold, MNR
中科院分区：
文献类型：
--
作者：
Cook, PA;Langford, SR;Ashfold, MNR
利用H/D原子光碎片平移光谱实验技术重新研究了H2S和D2 S的莱曼α（λ（H）= 121.6 nm）光解离。它们的总动能释放曲线由两个不同的组成部分组成。第一个是高度结构化的，被认为是两体解离为H/D（S-2）+ SH/SD（A（2）Sigma（+））片段，后者在一系列振转态中形成。通过分配这些不同的能级，确定D2 S的解离能（相对于产物的最低振转能级测量）为D-0（D-SD）大于或等于31 874+/-22 cm（-1）。第二个贡献，这是广泛的和相对非结构化的，是根据两个可能的碎裂途径建模;二次预解离的SH/SD（A（2）西格玛（+））的伴侣碎片与结构化的轮廓，和主要的三体解离为2 H/D（S-2）+ S（D-1）的原子产物。所提出的数据允许确定的动能依赖的各向异性参数（β），这是积极的两个配置文件。这表明H/D原子反冲速度在激光偏振轴上的优先平行分布。这些数据与从头算和经典轨道计算一起提出，这些计算试图解释基态H/D+SH/SD（X（2）Pi（Omega））分子产物缺乏分支。类似的通道在较轻同系物H2O的莱曼-α解离中是重要的。(C)2001年美国物理学会。
The Lyman-alpha (lambda (H) = 121.6 nm) photodissociation of both H2S and D2S has been reinvestigated using the experimental technique of H/D atom photofragment translational spectroscopy. Their total kinetic energy release profiles consist of two distinct components. The first, which is highly structured, is assigned to two body dissociation to H/D(S-2) + SH/SD(A (2)Sigma (+)) fragments, with the latter formed in a range of rovibrational states. By assigning these various levels the dissociation energy of D2S (measured relative to the lowest rovibrational level of the products) is determined to be D-0(D-SD) greater than or equal to 31 874+/-22 cm(-1). The second contribution, which is broad and relatively unstructured, is modeled in terms of two likely fragmentation pathways; secondary predissociation of SH/SD(A (2)Sigma (+)) partner fragments associated with the structured contour, and primary three-body dissociation to 2H/D(S-2) + S(D-1) atomic products. The presented data allow determination of the kinetic energy-dependent anisotropy parameter (beta), which is positive over both profiles. This indicates a preferentially parallel distribution of H/D atom recoil velocities about the laser polarization axis. These data are presented in tandem with ab initio and classical trajectory calculations which seek to explain the lack of branching to ground state H/D+SH/SD(X (2)Pi (Omega)) molecular products. The analogous channel is important in the Lyman-alpha dissociation of the lighter homologue, H2O. (C) 2001 American Institute of Physics.