Abstract

We present what we believe to be the first measurements of broadband XUV absorption spectroscopy with picosecond time scale resolution. A 10-Hz, 60 mJ 100-fs laser system is used to create a quasi-continuum of XUV radiation (30 Å < λ < 300 Å) from a gold plasmas to act as a probe source. The temporal duration of the probe is typically on the order of 20 ps but can be made shorter or longer by varying the laser parameters.¹ Part of the 100-fs laser beam also provides a delta-function pump beam to heat a sample onto which the XUV probe source is focused by a novel XUV imaging optics. Time-resolved results are gathered by two different methods: 1) a variable delay between the pump laser and the probe XUV source is used to collect spatially-resolved spectra of the sample's absorption at different times during the laser heating and 2) a unique jitter-free x-ray streak camera² developed at the Center for Ultrafast Optical Science is used to obtain temporally-resolved absorption spectra. This broadband time-resolved absorption spectroscopy technique offers a very interesting and flexible alternative to synchrotrons for experiments such as time-resolved EXAFS, chemical dynamics and ion characterization in laser ablation plumes.

© 1996 Optical Society of America