Soft x-ray imaging system for picosecond time-resolved absorption spectroscopy using a femtosecond-laser-plasma source

We have developed an imaging system for time-resolved soft x-ray absorption spectroscopy. The system consists of a femtosecond-laser-plasma x-ray source for time-resolved measurements and an x-ray microscope with critical illumination for imaging. The temporal and spatial resolutions were 23 ps and better than 12.5 mu m, respectively. We applied this system to the measurement of an aluminum ablation plume induced by irradiation with a 120 fs laser pulse. The shift of the L-shell photoabsorption edge in the expanding plume was observed in the spatiotemporally resolved absorbance spectrum. The space- and time-resolved x-ray absorption spectrum of an expanding laser ablation plume was clearly obtained using the developed system. (c) 2006 American Institute of Physics.