title: Structural preablation dynamics of graphite observed by ultrafast electron crystallography.
abstract: By means of time-resolved electron crystallography, we report direct observation of the structural dynamics of graphite, providing new insights into the processes involving coherent lattice motions and ultrafast graphene ablation. When graphite is excited by an ultrashort laser pulse, the excited carriers reach their equilibrium in less then one picosecond by transferring heat to a subset of strongly coupled optical phonons. The time-resolved diffraction data show that on such a time scale the crystal undergoes a contraction whose velocity depends on the excitation fluence. The contraction is followed by a large expansion which, at sufficiently high fluence, leads to the ablation of entire graphene layers, as recently predicted theoretically.
authors.affiliation: Physical Biology Center for Ultrafast Science & Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Carbone
authors.forename: Peter
authors.initials: P
authors.lastname: Baum
authors.forename: Petra
authors.initials: P
authors.lastname: Rudolf
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Zewail