[OPTICAL REVIEW Vol. 17, No. 3 (2010) 285-289]
© 2010 The Japan Society of Applied Physics

A Novel Double-Pulse Laser Plasma Spectroscopic Technique for H Analysis in Metal Samples Utilizing Transversely Excited Atmospheric-Pressure CO2 Laser-Induced Metastable He Atoms

Ali KHUMAENI, Zener Sukra LIE, Hideaki NIKI, Ken-ichi FUKUMOTO1, Tadashi MARUYAMA2, and Kiichiro KAGAWA1*

Program of Nuclear Power and Energy Safety Engineering, Graduate School of Engineering, University of Fukui, Fukui 910-8507, Japan
1Research Institute of Nuclear Engineering, University of Fukui, Fukui 910-8507, Japan
2Integrated Research Institute, Tokyo Institute of Technology, Yokohama 228-8503, Japan

(Received September 1, 2009; Accepted January 27, 2010)

The analysis of hydrogen in a metal sample (zircaloy-4), which is usually difficult to perform using conventional laser-induced breakdown spectroscopy (LIBS) techniques, has been achieved using a double-pulse technique under He gas at atmospheric pressure. In this technique, a transversely excited atmospheric-pressure (TEA) CO2 laser (1.5 J, 200 ns) was focused onto the metal surface to induce a strong He gas plasma whilst simultaneously focussing a Nd-doped yttrium aluminum garnet (Nd:YAG) laser (120 mJ, 8 ns), synchronized with the TEA CO2 laser, onto the metal to ablate atoms into the resulting He gas plasma. The emission spectrum obtained shows a narrow H linewidth with low background intensity and long lifetime emission, thereby indicating that excitation takes place via metastable He atoms. The H emission from H2O can be suppressed by a careful pretreatment involving heating the sample in a vacuum chamber.

Key words: hydrogen analysis, mismatching effect, double pulse technique, metastable He atoms, TEA CO2 laser, zircaloy-4

*E-mail address: kagawa@f-edu.u-fukui.ac.jp