Pulsed laser irradiation is used to heat deeply buried damage layers in diamond. Over a small range of laser powers, damage annealing, formation of buried graphitic layers, and melting of diamond followed by its conversion upon cooling into graphite are observed. The diagnostics employed are channeling contrast microscopy, optical absorption, surface profilometry, and scanning and optical microscopies. The results are explained in terms of the behavior of carbon under high internal pressures close to the diamond-graphite-liquid triple point in the phase diagram.

• Received 17 April 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.2991