J. Phys. IV France 11 (2001) Pr2-397-Pr2-403
Efficient soft X-ray generation from femtosecond-laser-produced plasma and its application to time resolved spectroscopyN. Uesugi1, H. Nakano2, T. Nishikawa2 and P. Lu3
1 Tohoku Institute of Techonology, 35-1 Yagiyama Kasumicho Taihaku-ku, Sendai 982-8577, Japan
2 NTT Basic Research Laboratories, 3-1 Wakamiya, Morinosato Atsugi-shi, Kanagawa 243-0198, Japan
3 Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Research Institute, 8-1-1-2 Umemidai, Kizucho, Souraku-gun, Kyoto-fu 619-0215, Japan
The experimental results on efficient soft x-ray generation from fs-laser-produced plasma and the application of short x-ray pulse to time-resolved spectroscopy are presented. Soft x-ray generation properties were evaluated for both flat Al targets and nanohole - alumina targets. The experimental results for flat metal targets revealed the fundamental properties of soft x-ray emission such as broadband continuum spectra and short pulse duration. By adopting nano-structured targets, a more than 30-hold enhancement of x-ray generation yield is achieved compared with that for flat targets of the same materials with a slight increase of pulse duration. The time-resolved measurement of the inner-shell absorption change of Si during the irradiation with a high-intensity fs laser pulse is achieved by using a short soft x-ray pulse as a probe pulse in pump-probe experiments for the first time. A more than 10% increase in the absorption of Si membrane at the Ln,m edge (around 100eV) was observed. The recovery time of the absorption change was measured to be about 20ps. This absorption change is assumed to be the bandgap renormarization of Si.
© EDP Sciences 2001