PICOSECOND AND SUBPICOSECOND LASER-HEATING OF ELECTRONS IN THE CONDUCTION-BAND OF SIO2

Photoelectron spectroscopy on an cu-quartz surface with intense subpic osecond laser pulses reveals strong differences between the spectra ob tained with two different wavelengths. For intensities above 100 GW/cm (2), a high-energy tail spreads out in the photoemission spectra at 62 0 nm, but no effect is observed at 310 nm, Multiple photon absorption by free electrons in the conduction band can explain the dependence of the spectra on the laser wavelength and intensity, and Monte Carlo si mulations including such mechanisms are in good agreement with the exp erimental results. (C) 1996 Optical Society of America