Autzen Olaf, Wesenberg Claudia, Hasselbrink Eckart
Fachbereich Chemie, Universität Duisburg-Essen, Germany.
Phys Rev Lett. 2006 May 19;96(19):196807. doi: 10.1103/PhysRevLett.96.196807. Epub 2006 May 17.
The surface photochemistry of on ultrathin epitaxial Ag films on Si(100) substrates has been studied with the goal to employ it as a tool to unravel the electron dynamics in such films. An increase of the photodesorption cross section is observed--a factor of 5 for 266 nm light and 12 nm film thickness--when the film thickness is decreased, despite the fact that the optical absorbtivity decreases. The increased photodesorption cross section is interpreted to result from photon absorption in the Si substrate producing electrons at energies and parallel momenta which are not allowed in Ag. These electrons penetrate through the Ag film despite the gap in the surface projected band structure utilizing quantum resonances.
对硅（100）衬底上超薄外延银膜的表面光化学进行了研究，目的是将其用作揭示此类薄膜中电子动力学的工具。尽管光吸收率降低，但当薄膜厚度减小时，观察到光解吸截面增加——对于266nm光和12nm薄膜厚度，增加了5倍。光解吸截面的增加被解释为是由于硅衬底中的光子吸收产生了能量和横向动量在银中不允许的电子。尽管表面投影能带结构存在能隙，但这些电子利用量子共振穿透了银膜。
