submitted papers Quantitative Deuterium Analysis of Titanium Samples in Ultraviolet Laser-Induced Low-Pressure Helium Plasma SYAHRUN NUR ABDULMADJID, ZENER SUKRA LIE, HIDEAKI NIKI, MARINCAN PARDEDE, RINDA HEDWIG, TJUNG JIE LIE, ERIC JOBILIONG, KOO HENDRIK KURNIAWAN,* KEN-ICHI FUKUMOTO, KIICHIRO KAGAWA, and MAY ON TJIA Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 43111, Nanggroe Aceh Darussalam, Indonesia (S.N.A.); Department of Nuclear Power and Energy Safety Engineering, University of Fukui, Fukui 910-8507, Japan (Z.S.L., H.N.); Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Kembangan RT 02 RW 06, Jakarta Barat 11630, Indonesia (M.P., R.H., T.J.L., E.J., K.H.K.); Research Institute of Nuclear Engineering, University of Fukui, Fukui 910-8507, Japan (K.-I.F.); Department of Physics, Faculty of Education and Regional Studies, Fukui University, 9-1 bunkyo 3-chome, Fukui 910-8507, Japan (K.K.); Physics of Magnetism and Photonics Research Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132, Indonesia (M.O.T.) An experimental study of ultraviolet (UV) laser-induced plasma spectros- copy (LIPS) on Ti samples with low-pressure surrounding He gas has been carried out to demonstrate its applicability to quantitative micro-analysis of deuterium impurities in titanium without the spectral interference from the ubiquitous surface water. This was achieved by adopting the optimal experimental condition ascertained in this study, which is specified by 5 mJ laser energy, 10 Torr helium pressure, and 1–50 ls measurement window, which resulted in consistent D emission enhancement and effective elimination of spectral interference from surface water. As a result, a linear calibration line exhibiting a zero intercept was obtained from Ti samples doped with various D impurity concentrations. An additional measurement also yielded a detection limit of about 40 ppm for D impurity, well below the acceptable threshold of damaging H concentration in Ti and its alloys. Each of these measurements was found to produce a crater size of only 25 lm in diameter, and they may therefore qualify as nondestructive measurements. The result of this study has therefore paved the way for conducting further experiments with hydrogen-doped Ti samples and the technical implementation of quantitative micro-analysis of detrimental hydrogen impurity in Ti metal and its alloys, which is the ultimate goal of this study. Index Headings: Hydrogen analysis; Deuterium analysis; Titanium sample; Laser-induced breakdown spectroscopy; LIBS; Helium surrounding gas. INTRODUCTION In a recent study, 1 the widely adopted practical technique of laser-induced breakdown spectroscopy (LIBS) 2–9 was shown to be applicable to address the urgent need for regular, rapid, and in situ quantitative analysis of detrimental hydrogen impurities penetrated into the zircaloy wall of the fuel vessels of a light- water nuclear power plant. In contrast to the unacceptably broad and weak H emission commonly observed in conven- tional LIBS operated with ambient air, 10,11 the study reported the observation of a remarkable sharp hydrogen emission line when the atmospheric-pressure ambient air used in standard LIBS was replaced by a low-pressure helium gas. Subsequent- ly, the interfering H emission from the ubiquitous surface water and surrounding gas was largely reduced by proper defocusing of the laser irradiation as well as the proper control of ambient air pressure and chamber temperature, which resulted in a linear intensity calibration line. 12,13 In a more recent study, 14 doped deuterium impurities in a zircaloy-4 sample were used as a surrogate for H impurities for the investigation of different and distinct characteristics exhibited by the emission of H impurities and that of the dissociated surface water, and the experimental conditions most favorable for the detection of H impurity emission while suppressing the interfering H emission were thereby determined. The result of using that optimal experimental condition yielded a further suppression of the interfering H emission by a factor of 10, although this was achieved at a cost of reduced linear dynamical range. Titanium (Ti) and its alloys are also known to suffer from similar problems with the presence of H impurities in the material, and they must therefore be routinely examined to avoid intolerable dysfunction of the material. The metal and its alloys are known to have wide-ranging and sometimes irreplaceable applications as medical materials in the form of pure Ti, as well as industrial materials in the form of its alloys. It is therefore natural to investigate the applicability or the needed modification of the previously developed technique reported in Ref. 14 for hydrogen analysis of Ti samples, in particular the non-alloyed Ti materials used for medical purposes, where the generally low tolerances to H impurity- induced detrimental effects must be strictly observed. Our preliminary experiment has indicated that such an extension requires a study beyond a straightforward adjustment or adaptation of the optimal experimental parameters obtained previously for zircaloy samples. 1,12–14 In fact, no plasma was observed when the Ti sample was irradiated using the Nd:YAG laser at its fundamental wavelength at various energies up to 30 mJ, very much like the cases with Pb and W found in our previous study in which only the ablation effect was observed. Received 16 November 2009; accepted 26 January 2010. * Author to whom correspondence should be sent. E-mail: kurnia18@ cbn.net.id. Volume 64, Number 4, 2010 APPLIED SPECTROSCOPY 365 0003-7028/10/6404-0365$2.00/0 Ó 2010 Society for Applied Spectroscopy