Size-Dependent Electron Dynamics of Gold Nanoparticles

2019-05-29 05:59:34

absorption plasmon electron dynamics phonon

责任者: Ahmadi, Temer S.;Logunov, Stephan L.;El-Sayed, Mostafa A. 单位: School of Chemistry and Biochemistry, Laser Dynamics Laboratory, Georgia Institute of Technology, Atlanta, GA 30332-0400, United States 来源出处: ACS Symposium Series,1997,679():125-140 摘要: The electron dynamics of four samples of colloidal gold nanoparticle with average particle diameter of 1.5, 2.5, 3.3, and 30 nm are studied by transient absorption spectroscopy after excitation with 400 fs laser pulses at 600 nm wavelength. Photoexcitation leads to the bleach of the surface plasmon (intraband) and 5d->6sp interband transition. The temporal relaxation of the electron gas of metallic nanoparticles at the peak of plasmon band absorption follows a biexponential kinetics with a 2.5 ps and >50 ps components which are attributed to thermalization of the photoexcited non-fermi hot electron gas through electron-phonon and phonon-phonon interactions, respectively. No direct observation of electron-electron relaxation was possible because this process occurs within the duration of our laser pulse. There is a size-dependent shift in the maximum of steady-state absorption and the transient minimum of the plasmon bleach which is attributed to quantum size effect in the smaller particles. 关键词: ;