Fakultät für Chemie and Centre for Nanointegration (CeNIDE), Universität Duisburg-Essen, D-45117 Essen, Germany.
J Chem Phys. 2011 Jan 21;134(3):034705. doi: 10.1063/1.3523647.
Associated with chemical reactions at surfaces energy may be dissipated exciting surface electronic degrees of freedom. These excitations are detected using metal-insulator-metal (MIM) heterostructures (Ta-TaOx-Au) and the reactions of H with and on a Au surface are probed. A current corresponding to 5×10(-5) electrons per adsorbing H atom and a marked isotope effect are observed under steady-state conditions. Analysis of the current trace when the H atom flux is intermitted suggests that predominantly the recombination reaction creates electronic excitations. Biasing the front versus the back electrode of the MIM structure provides insights into the spectrum of electronic excitations. The observed spectra differ for the two isotopes H and D and are asymmetric when comparing negative and positive bias voltages. Modeling indicates that the excited electrons and the concurrently created holes differ in their energy distributions.
与表面化学反应相关，能量可能会耗散激发表面电子自由度。这些激发是通过金属-绝缘体-金属（MIM）异质结构（Ta-TaOx-Au）来检测的，并探测了 H 在 Au 表面上的反应。在稳态条件下，观察到与每个吸附 H 原子对应的 5×10(-5)个电子的电流和显著的同位素效应。当 H 原子通量中断时对电流轨迹的分析表明，主要是复合反应产生了电子激发。相对于 MIM 结构的前电极和后电极偏置提供了对电子激发谱的深入了解。观察到的光谱因两种同位素 H 和 D 而不同，并且当比较负偏压和正偏压时，光谱是不对称的。建模表明，激发电子和同时产生的空穴在其能量分布上存在差异。
