Ken-ichiro Yomogihata

Tohoku University, Sendai, Kagoshima, Japan

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Publications (2)4.48 Total impact

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    ABSTRACT: We have generated hard X-rays by front- and back-side femtosecond laser irradiation of PbO-rich glass. The actual Pb content of glasses was corroborated by Pb M-line emission intensities with an uncertainty of less than 20%. The elements K and As at concentrations of a few mol% were detected. X-ray generation by back-side irradiation helped to avoid an air breakdown; however, self-focusing and filamentation limited the achievable light intensity and effectiveness of X-ray generation. Characteristics and mechanisms of X-ray generation from the front- and back-side of glasses are discussed.
    No preview · Article · Dec 2008 · Journal of Non-Crystalline Solids
  • Koji Hatanaka · Ken-ichiro Yomogihata · Hiroshi Ono · Hiroshi Fukumura
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    ABSTRACT: Various material surfaces were irradiated on a moving stage with focused laser pulses from a conventional 1 kHz femtosecond laser system, and X-ray emission spectra were measured during the laser ablation of the materials. Sharp K or L characteristic X-ray lines from the elements contained in the materials were clearly observed in a range of 2–15 keV. Signals due to copper and zinc were recognizable within a few minutes when a brass surface was irradiated. Poly(vinyl chloride) gave a marked emission originating from chlorine. When a color glass filter was irradiated, the detection of cobalt and arsenic was possible even though the amounts of these components were estimated to be less than 1 wt.% by using an electron probe microanalyzer. Time-integrated emission spectra in the visible region were also monitored during the femtosecond laser ablation of these materials. The emission spectra in the visible region were complicated owing to peaks originating from air components and white continuum emissions. Thus, the elemental analysis by femtoseond laser induced X-ray is considered to be useful for some samples. The etched trenches left at the surfaces after the laser ablation were examined with an optical microscope. The trench width varied with the materials, which may be attributed to changes in the irradiation area giving maximum counts of X-ray emission.
    No preview · Article · Jul 2005 · Applied Surface Science