title: Ultrafast spatiotemporal relaxation dynamics of excited electrons in a metal nanostructure detected by femtosecond-SNOM.
abstract: Ultrahigh spatiotemporal resolved pump-probe signal near a gold nano-slit is detected by femtosecond-SNOM. By employing two-color pump-probe configuration and probing at the interband transition wavelength of the gold, signal contributed by surface plasmon polariton is avoided and spatiotemporal evolvement of excited electrons is successfully observed. From the contrast decaying of the periodical distribution of the pump-probe signal, ultrafast diffusion of excited electrons with a time scale of a few hundred femtoseconds is clearly identified. For comparison, such phenomenon cannot be observed by the one-color pump-probe configuration.
authors.affiliation: State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing, China. lazyli@pku.edu.cn
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.forename: Song
authors.initials: S
authors.lastname: Yue
authors.forename: Jianjun
authors.initials: J
authors.lastname: Chen
authors.forename: Qihuang
authors.initials: Q
authors.lastname: Gong
mesh_terms: D004583:Electrons; D004867:Equipment Design; D006046:Gold; D053768:Metal Nanoparticles; D008853:Microscopy / Q000295:instrumentation / Q000379:methods*; D049329:Nanostructures; D036103:Nanotechnology / Q000379:methods*; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods*
chemical_list: D006046:Gold