Attosecond Electron Processes in Materials: Excitons, Plasmons, and Charge Dynamics.

摘要

A five year program focusing on investigation of attosecond electron dynamics in solid state materials is completed. Two experimental apparatuses for attosecond time-resolved extreme ultraviolet (XUV) studies were constructed. Highlights of results are: a 450 attosecond electronic response time in the conduction band of silicon was experimentally measured by observing steps in the L2,3-edge spectrum of silicon, synchronized with the excitation laser electric field. Independent electron and hole dynamics were observed in germanium by time-resolved ultrafast measurements on the M4,5-edge spectrum of germanium. A near-instantaneous spectral response over a broad range around the vanadium M2,3-edge, followed by a fast reshaping of the spectrum, was observed in VO2, suggesting a signature of the ultrafast insulator to metal transition.