Surface Reaction Dynamics Studied by Hot-atom Beams

1.甲烷在铂(111)面光化学反应的激发机理：吸附在铂(111)面上的甲烷被193 nm的光子解离。通过激光偏振随入射角变化的截面测量，研究了激光的激发机制。我们发现直接励磁起着重要的作用。甲烷在铂(111)面上光解产生的能化氢原子与预吸附的甲基进一步反应生成甲烷，然后将能量耗散到载体上。用脉冲加热和飞行时间法研究了氢与甲烷在铂(111)面上的热致复合反应动力学。该反应产生的甲烷解吸的平均动能为0.43 eV，沿表面法线的角分布非常尖锐。将所得结果与基于RRKM理论的模型预测结果进行了比较。

1. Excitation mechanism for photochemistry of methane on Pt (111).Methane adsorbed on Pt (111) surface is dissociated with 193 nm photons. The excitation mechanism was investigated by cross section measurements with a fixed polarization of laser as a function of incident angles. We found that direct excitation plays an important role.2. Photo-induced recombination reaction between hot H atoms and methyl adsorbates.Energetic hydrogen atoms produced via photodissociation of methane on Pt (111) further react with pre-adsorbed methyl to form methane before they dissipate energy to the bulk.3. Dynamics of the thermally induced recombination reaction between H and CH_3.Recombination reaction between hydrogen and methyl adsorbates on Pt (111) was investigated by pulse heating and TOF measurements. Methane produced by this reaction desorbs with the average kinetic energy of 0.43 eV.The angular distribution of methane is quite sharp along the surface normal. The obtained results were compared with the predictions of a model based on RRKM theory.