OPTICAL ANISOTROPY AS A TECHNIQUE FOR STUDYING ULTRAFAST PHASE-TRANSFORMATIONS AT SOLID-SURFACES

A new technique for testing long-range order in high-absorption anisot ropic crystals has been developed using conversion of an incident p- ( s-)wave to an s- (p-)wave due to optical anisotropy. The technique yie lds time-resolved measurements of parameters related to phase transfor mations in thin (10(-6)-10(-5) cm) layers with a high resolution (10(- 12) s). Using picosecond laser pulses and an ''Agat'' streak camera, t he technique has been applied to an experimental investigation of melt ing and recrystallization kinetics at zinc and graphite surfaces. It w as found that the process of melting takes less than 3 ps and the recr ystallization time is about 100 ps. (C) 1998 American Institute of Phy sics.