title: Ultrafast relaxation of excited Dirac fermions in epitaxial graphene using optical differential transmission spectroscopy.
abstract: We investigate the ultrafast relaxation dynamics of hot Dirac fermionic quasiparticles in multilayer epitaxial graphene using ultrafast optical differential transmission spectroscopy. We observe differential transmission spectra which are well described by interband transitions with no electron-hole interaction. Following the initial thermalization and emission of high-energy phonons, the electron cooling is determined by electron-acoustic phonon scattering, found to occur on the time scale of 1 ps for highly doped layers, and 4-11 ps in undoped layers. The spectra also provide strong evidence for the multilayer structure and doping profile of thermally grown epitaxial graphene on SiC.
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Sun
authors.forename: Zong-Kwei
authors.initials: ZK
authors.lastname: Wu
authors.forename: Charles
authors.initials: C
authors.lastname: Divin
authors.forename: Xuebin
authors.initials: X
authors.lastname: Li
authors.forename: Claire
authors.initials: C
authors.lastname: Berger
authors.forename: Walt A
authors.initials: WA
authors.lastname: de Heer
authors.forename: Phillip N
authors.initials: PN
authors.lastname: First
authors.forename: Theodore B
authors.initials: TB
authors.lastname: Norris