Abstract

Because of the simple quasi-two-dimensional structure [1] and small overlap of the valence-and conduction band in highly oriented pyrolytic graphite (HOPG) the relaxation dynamic of nonequilibrium electronic carriers should differ distinctly from that already observed in semiconductors. Because of its short absorption depth (30 nm) hot carrier populations denser than 10²²cm^-3 can be easily generated with amplified fs-pulses at λ = 625nm. We report the first femtosecond time-resolved spectroscopy of carrier generation and relaxation in HOPG over a wide range of optical excitation densities using white light continuum probing.

© 1990 Optical Society of America