title: Electron dynamics of silicon surface states: second-harmonic hole burning on Si(111)-(7 x 7).
abstract: We report the first all-optical study of homogeneous linewidths of surface excitations by the spectral-hole-burning technique with surface-specific second-harmonic generation as a probe. Measurement of transient spectral holes induced by a 100 fs pump pulse in excitations of the surface dangling-bond states of Si(111)-(7 x 7) led to a pump-fluence-dependent homogeneous linewidth as broad as approximately 100 meV or a dephasing time as short as 15 fs. The hole-burning spectra also revealed a strong coupling between the localized dangling-bond states and the associated surface phonon mode at 570 cm(-1). Carrier-carrier scattering was responsible for the linear dependence of the dephasing rate on pump fluence, and the carrier screening effect appeared to be weak.
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: McGuire
authors.forename: Markus B
authors.initials: MB
authors.lastname: Raschke
authors.forename: Y Ron
authors.initials: YR
authors.lastname: Shen