Spectroscopy of solid density plasmas generated by irradiation of thin foils by a fs laser

We present time-resolved spectroscopy of laser-produced plasmas achieved wi th a 500 fs resolution. Time history of Al It-shell emission from hot solid density plasmas produced by the interaction of an intense subpicosecond la ser pulse (150-400 fs, 0.53 mu m, 5 x 10(18) W/cm(2)) with a thin free-stan ding foil target (500-1000 Angstrom) appears to change drastically with las er pulse duration, the X-ray emission duration decreasing with the heating pulse duration. We report here what we believe to be the first observations of subpicosecond thermal X-ray emissions (Al He-alpha, 500-700 fs) in lase r-produced plasmas. Such results are of interest for applications to the ob servation of ultrafast phenomena in matter. (C) 2000 Elsevier Science Ltd. All rights reserved.