A phase transformation in graphite irradiated by visible picosecond laser pulses is observed above a well-defined pump threshold. Time-resolved reflectivity measurements at different wavelengths indicate that the high-temperature phase is not metallic. At low irradiation levels, a fast decaying plasma component is observed.

• Received 17 March 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.146