Koszinowski Konrad, Goldberg Noah T, Pomerantz Andrew E, Zare Richard N
Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
J Chem Phys. 2006 Oct 7;125(13):133503. doi: 10.1063/1.2217742.
We describe a new instrument based on a delay-line detector for imaging the complete three-dimensional velocity distribution of photoionized products from photoinitiated reactions. Doppler-free [2+1] resonantly enhanced multiphoton ionization (REMPI) of H and D atoms formed upon photolysis of HBr and DBr in the range 203 nm < or = lambda photolysis < or = 243 nm yields radial speeds measured to be accurate within 1% of those calculated. The relative speed resolution is about 5% and limited by photoionization recoil broadening. A relative speed resolution of 3.4% is obtained for [3+1] REMPI, which minimizes the ionization recoil. We also determine the branching ratio between ground-state and spin-orbit-excited product channels and their associated anisotropies. We find that DBr photolysis dynamics differs slightly from its HBr counterpart.
我们描述了一种基于延迟线探测器的新仪器，用于对光引发反应中光离子化产物的完整三维速度分布进行成像。在203nm≤λ光解≤243nm范围内，对HBr和DBr光解形成的H和D原子进行无多普勒[2 + 1]共振增强多光子电离（REMPI），得到的径向速度测量值与计算值的误差在1%以内。相对速度分辨率约为5%，受光离子化反冲展宽限制。对于[3 + 1] REMPI，相对速度分辨率为3.4%，可使电离反冲最小化。我们还确定了基态和自旋轨道激发产物通道之间的分支比及其相关的各向异性。我们发现DBr光解动力学与其HBr对应物略有不同。
