Nanomodification of gold surface by picosecond soft X-ray laser pulse

ピコ秒軟X線レーザーパルスによる金表面のナノ構造変調

Norman, G.*; Starikov, S.*; Stegailov, V.*; Fortov, V.*; Skobelev, I.*; Pikuz, T. A.; Faenov, A.*; 保 智己*; 加藤 義章* ; 石野 雅彦; 田中 桃子; 長谷川 登; 錦野 将元; 大場 俊幸*; 海堀 岳史; 越智 義浩; 今園 孝志; 福田 祐仁; 神門 正城; 河内 哲哉

Norman, G.*; Starikov, S.*; Stegailov, V.*; Fortov, V.*; Skobelev, I.*; Pikuz, T. A.; Faenov, A.*; Tamotsu, Satoshi*; Kato, Yoshiaki*; Ishino, Masahiko; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Oba, Toshiyuki*; Kaihori, Takeshi; Ochi, Yoshihiro; Imazono, Takashi; Fukuda, Yuji; Kando, Masaki; Kawachi, Tetsuya

It was shown experimentally the possibility of nanostructuring (about 20 nm) of gold surface by picosecond soft X-ray single pulse with low fluence of 20 mJ/cm. The nanometer-scale changes of the surface structure are due to the splash of molten gold under fluence gradient of the laser beam. In addition, the ablation process occurs at slightly higher fluence of 50 mJ/cm. The atomistic model of ablation is developed that reveals that the low threshold fluence of this process is due to the build-up of the high electron pressure and the comparatively low electron-ion energy relaxation rate in gold.