Alexander William A, Morris John R, Troya Diego
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061-0212, USA.
J Chem Phys. 2009 Feb 28;130(8):084702. doi: 10.1063/1.3072012.
We present an experimental and theoretical study of the dynamics of collisions of the CO molecule with organic surfaces. Experimentally, we scatter CO at 60 kJ mol(-1) and 30 degrees incident angle from regular (CH(3)-terminated) and omega-fluorinated (CF(3)-terminated) alkanethiol self-assembled monolayers (SAMs) and measure the time-of-flight distributions at the specular angle after collision. At a theoretical level, we carry out classical-trajectory simulations of the same scattering process using CO/SAM potential-energy surfaces derived from ab initio calculations. Agreement between measured and calculated final translational energy distributions justifies use of the calculations to examine dynamical behavior of the gas/surface system not available directly from the experiment. Calculated state-to-state energy-transfer properties indicate that the collisions are notably vibrationally adiabatic. Similarly, translational energy transfer from and to CO rotation is relatively weak. These trends are examined as a function of collision energy and incident angle to provide a deeper understanding of the factors governing state-to-state energy transfer in gas/organic-surface collisions.
我们展示了一项关于CO分子与有机表面碰撞动力学的实验和理论研究。实验方面，我们以60 kJ mol(-1)的能量和30度的入射角，将CO从规则的（以CH(3)结尾的）和ω-氟化的（以CF(3)结尾的）烷硫醇自组装单分子层（SAMs）上散射，并测量碰撞后镜面角处的飞行时间分布。在理论层面，我们使用从从头算计算得出的CO/SAM势能面，对相同的散射过程进行经典轨迹模拟。测量和计算得到的最终平动能量分布之间的一致性，证明了使用这些计算来研究无法直接从实验获得的气体/表面系统动力学行为的合理性。计算得到的态对态能量转移性质表明，碰撞在振动方面明显是绝热的。同样，CO转动的平动能转移相对较弱。我们研究了这些趋势作为碰撞能量和入射角的函数，以更深入地理解在气体/有机表面碰撞中控制态对态能量转移的因素。
