Abstract

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 (1s¹ 3d¹). 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.

Direct evidence of laser-induced shock wave plasma from organic targets in low pressure He ambient gas, showing the effect of target hardness on its propagation speed and the resulted spectral performance

Kurnia Lahna, Marincan Pardede, Koo Hendrik Kurniawan, Kiichiro Kagawa, and May On Tjia
Appl. Opt. 56(36) 9876-9881 (2017)

Suppression of self-absorption effect in laser-induced breakdown spectroscopy by employing a Penning-like energy transfer process in helium ambient gas

Rinda Hedwig, Ivan Tanra, Indra Karnadi, Marincan Pardede, Alion Mangasi Marpaung, Zener Sukra Lie, Koo Hendrik Kurniawan, Maria Margaretha Suliyanti, Tjung Jie Lie, and Kiichiro Kagawa
Opt. Express 28(7) 9259-9268 (2020)

Formation and emission characteristics of CN molecules in laser induced low pressure He plasma and its applications to N analysis in coal and fossilization study

Kurnia Lahna, Rinaldi Idroes, Nasrullah Idris, Syahrun Nur Abdulmadjid, Koo Hendrik Kurniawan, May On Tjia, Marincan Pardede, and Kiichiro Kagawa
Appl. Opt. 55(7) 1731-1737 (2016)

Toward the optimization of double-pulse LIBS underwater: effects of experimental parameters on the reproducibility and dynamics of laser-induced cavitation bubble

Gabriele Cristoforetti, Marco Tiberi, Andrea Simonelli, Paolo Marsili, and Francesco Giammanco
Appl. Opt. 51(7) B30-B41 (2012)

Plasma emission characteristics in laser-induced breakdown spectroscopy of silicon with mid-infrared, multi-millijoule, nanosecond laser pulses from a Ho:YLF excitation source

Rotem Kupfer, Hernan J. Quevedo, Herbie L. Smith, Thanh N. Ha, Andrew Yandow, Ganesh Tiwari, C. Grant Richmond, Li Fang, and B. Manuel Hegelich
Appl. Opt. 58(17) 4592-4598 (2019)