title: Spectral and dynamic characteristics of helium plasma emission and its effect on a laser-ablated target emission in a double-pulse laser-induced breakdown spectroscopy (LIBS) experiment.
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 (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.
authors.affiliation: Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811, Indonesia.
authors.forename: Eric
authors.initials: E
authors.lastname: Jobiliong
authors.forename: Hery
authors.initials: H
authors.lastname: Suyanto
authors.forename: Alion Mangasi
authors.initials: AM
authors.lastname: Marpaung
authors.forename: Syahrun Nur
authors.initials: SN
authors.lastname: Abdulmadjid
authors.forename: Nasrullah
authors.initials: N
authors.lastname: Idris
authors.forename: Rinda
authors.initials: R
authors.lastname: Hedwig
authors.forename: Muliadi
authors.initials: M
authors.lastname: Ramli
authors.forename: Marincan
authors.initials: M
authors.lastname: Pardede
authors.forename: Maria Margaretha
authors.initials: MM
authors.lastname: Suliyanti
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Kagawa
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Fukumoto
authors.forename: May On
authors.initials: MO
authors.lastname: Tjia
authors.forename: Tjung Jie
authors.initials: TJ
authors.lastname: Lie
authors.forename: Zener Sukra
authors.initials: ZS
authors.lastname: Lie
authors.forename: Koo Hendrik
authors.initials: KH
authors.lastname: Kurniawan