Perkins Bradford G, Nesbitt David J
JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0440, USA.
Proc Natl Acad Sci U S A. 2008 Sep 2;105(35):12684-9. doi: 10.1073/pnas.0800401105. Epub 2008 Aug 4.
Stereodynamics at the gas-liquid interface provides insight into the important physical interactions that directly influence heterogeneous chemistry at the surface and within the bulk liquid. We investigate molecular beam scattering of CO(2) from a liquid perfluoropolyether (PFPE) surface in vacuum [incident energy E(inc) = 10.6(8) kcal/mol, incident angle theta(inc) = 60 degrees] to specifically reveal rotational angular-momentum directions for scattered molecules. Experimentally, internal quantum state populations and M(J) distributions are probed by high-resolution polarization-modulated infrared laser spectroscopy. Analysis of J-state populations reveals dual-channel scattering dynamics characterized by a two-temperature Boltzmann distribution for trapping-desorption and impulsive scattering. In addition, molecular dynamics simulations of CO(2) + fluorinated self-assembled monolayers have been used to model CO(2) + PFPE dynamics. Experimental results and molecular dynamics simulations reveal highly oriented CO(2) distributions that preferentially scatter with "top spin" as a strongly increasing function of J state.
气液界面的立体动力学为直接影响表面和本体液体中多相化学的重要物理相互作用提供了深入见解。我们研究了真空中二氧化碳（CO₂）从液态全氟聚醚（PFPE）表面的分子束散射[入射能量E(inc) = 10.6(8)千卡/摩尔，入射角θ(inc) = 60度]，以具体揭示散射分子的旋转角动量方向。在实验中，通过高分辨率偏振调制红外激光光谱探测内部量子态布居和M(J)分布。对J态布居的分析揭示了双通道散射动力学，其特征是捕获-解吸和脉冲散射的双温度玻尔兹曼分布。此外，二氧化碳（CO₂）与氟化自组装单分子层的分子动力学模拟已被用于模拟二氧化碳（CO₂）与全氟聚醚（PFPE）的动力学。实验结果和分子动力学模拟揭示了高度取向的二氧化碳（CO₂）分布，其优先以“顶旋”方式散射，且作为J态的强递增函数。
