Jobiliong Eric, Suyanto Hery, Marpaung Alion Mangasi, Abdulmadjid Syahrun Nur, Idris Nasrullah, Hedwig Rinda, Ramli Muliadi, Pardede Marincan, Suliyanti Maria Margaretha, Kagawa Kiichiro, Fukumoto Ken-Ichi, Tjia May On, Lie Tjung Jie, Lie Zener Sukra, Kurniawan Koo Hendrik
Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811, Indonesia.
Appl Spectrosc. 2015 Jan;69(1):115-23. doi: 10.1366/14-07489. Epub 2014 Dec 1.
A systematic study has been performed on the spectral characteristics of the full spectrum of He emission lines and their time-dependent behaviors measured from the He gas plasmas generated by a nanosecond neodymium-doped yttrium aluminum garnet laser. It is shown that among the major emission lines observed, the triplet He(I) 587.6 nm emission line stands out as the most prominent and long-lasting line, associated with de-excitation of the metastable triplet (S = 1) excited state (1s(1) 3d(1)). The role of this metastable excited state is manifested in the intensity enhancement and prolonged life time of the Cu emission with narrow full width half-maximum, as demonstrated in an orthogonal double-pulse experiment using a picosecond laser for the target ablation and a nanosecond laser for the prior generation of the ambient He gas plasma. These desirable emission features are in dire contrast to the characteristics of emission spectra observed with N2 ambient gas having no metastable excited state, which exhibit an initial Stark broadening effect and rapid intensity diminution typical to thermal shock wave-induced emission. The aforementioned He metastable excited state is therefore responsible for the demonstrated favorable features. The advantage of using He ambient gas in the double-pulse setup is further confirmed by the emission spectra measured from a variety of samples. The results of this study have thus shown the potential of extending the existing laser-induced breakdown spectroscopy application to high-sensitivity and high-resolution spectrochemical analysis of wide-ranging samples with minimal destructive effect on the sample surface.
对由纳秒掺钕钇铝石榴石激光产生的氦气等离子体中测量的氦发射线全谱的光谱特性及其随时间的行为进行了系统研究。结果表明,在所观察到的主要发射线中,三重态氦(I)587.6nm发射线是最突出且持续时间最长的线,与亚稳三重态(S = 1)激发态(1s(1) 3d(1))的去激发有关。这种亚稳激发态的作用体现在铜发射强度的增强和半高宽较窄的寿命延长上,这在使用皮秒激光进行靶材烧蚀和纳秒激光用于预先产生周围氦气等离子体的正交双脉冲实验中得到了证明。这些理想的发射特征与在没有亚稳激发态的氮气环境气体中观察到的发射光谱特征形成了鲜明对比,后者表现出初始斯塔克展宽效应和热冲击波诱导发射典型的快速强度衰减。因此,上述氦亚稳激发态是所展示的有利特征的原因。在双脉冲设置中使用氦环境气体的优势通过从各种样品测量的发射光谱进一步得到证实。这项研究的结果因此显示了将现有的激光诱导击穿光谱应用扩展到对广泛样品进行高灵敏度和高分辨率光谱化学分析的潜力,同时对样品表面的破坏作用最小。