An axis-specific rotational rainbow in the direct scatter of formaldehyde from Au(111) and its influence on trapping probability.
An axis-specific rotational rainbow in the direct scatter of formaldehyde from Au(111) and its influence on trapping probability.
复制标题
DOI：
10.1039/c7cp03922k
复制
发表时间：
2017-08
期刊：
影响因子：
--
通讯作者：
G. B. Park;Bastian C. Krüger;S. Meyer;A. Kandratsenka;A. Wodtke;Tim Schäfer
中科院分区：
文献类型：
--
作者：
G. B. Park;Bastian C. Krüger;S. Meyer;A. Kandratsenka;A. Wodtke;Tim Schäfer
平移到旋转运动的转换通常在表面捕获小分子中起着重要作用，这是发生在气体-表面界面的各种化学过程的关键第一步。然而，到目前为止，大多数量子态分辨表面散射实验已经进行了双原子分子，和小的详细信息是如何的非线性多原子分子的结构影响的机制与表面的能量交换。本文采用一种新的旋转分辨1 + 1'共振增强多光子电离（REMPI）方案，测量了入射动能在0.3-1.2 eV范围内，甲醛分子从Au（111）表面直接散射的转动分布。结果表明，一个显着的倾向，激发a轴旋转（旋转），而不是B-或c-轴旋转（翻滚或侧手翻），并与旋转彩虹散射模型是一致的。经典的轨道计算表明，该效应从分子的三维形状（空间效应）到零级。分析表明，高度的旋转激发有一个重大的影响，在入射平移能量超过0.5 eV的甲醛的捕获概率。
The conversion of translational to rotational motion often plays a major role in the trapping of small molecules at surfaces, a crucial first step for a wide variety chemical processes that occur at gas-surface interfaces. However, to date most quantum-state resolved surface scattering experiments have been performed on diatomic molecules, and little detailed information is available about how the structure of nonlinear polyatomic molecules influences the mechanisms for energy exchange with surfaces. In the current work, we employ a new rotationally resolved 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme to measure the rotational distribution in formaldehyde molecules directly scattered from the Au(111) surface at incidence kinetic energies in the range 0.3-1.2 eV. The results indicate a pronounced propensity to excite a-axis rotation (twirling) rather than b- or c-axis rotation (tumbling or cartwheeling), and are consistent with a rotational rainbow scattering model. Classical trajectory calculations suggest that the effect arises-to zeroth order-from the three-dimensional shape of the molecule (steric effects). Analysis suggests that the high degree of rotational excitation has a substantial influence on the trapping probability of formaldehyde at incidence translational energies above 0.5 eV.