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

G Norman and S Starikov and V Stegailov and V Fortov and I Skobelev and T Pikuz and A Faenov and S Tamotsu and Y Kato and M Ishino and M Tanaka and N Hasegawa and M Nishikino and T Ohba and T Kaihori and Y Ochi and T Imazono and Y Fukuda and M Kando and T Kawachi, JOURNAL OF APPLIED PHYSICS, 112, 013104 (2012).

DOI: 10.1063/1.4731752

We show experimentally the possibility of nanostructuring (about 20 nm) of gold surface by picosecond soft x-ray single pulse with low fluence of similar to 20 mJ/cm(2). 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 similar to 50 mJ/cm(2). The atomistic model of ablation is developed which 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. The calculated ablation depths as a function of the irradiation fluence are in good agreement with the experimental data measured for gold surface modification with ultra-short duration soft x-ray and visible lasers. (C) 2012 American Institute of Physics.

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