Transient observation of extended x-ray absorption fine structure in laser-melted Si by using femtosecond laser-produced-plasma soft x ray

We have demonstrated the time-resolved measurement of the extended x-ray absorption fine structure (EXAFS) in laser-melted Si foil by using a pump-probe absorption spectroscopy system that utilizes a femtosecond laser-produced-plasma soft x-ray source. By using 100-fs laser irradiation, we observed the transient change in the Si L-edge EXAFS, that is, a slight shortening of its oscillation period and a decrease in its oscillation amplitude. This result suggests that the Si-Si atomic distance expanded and structural disordering occurred as a result of the production of liquid Si. (c) 2005 American Institute of Physics.