title: A comparative study of pressure-dependent emission characteristics in different gas plasmas induced by nanosecond and picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers.
abstract: An experimental study has been performed on the pressure-dependent plasma emission intensities in Ar, He, and N2 surrounding gases with the plasma induced by either nanosecond (ns) or picosecond (ps) yttrium aluminum garnet laser. The study focused on emission lines of light elements such as H, C, O, and a moderately heavy element of Ca from an agate target. The result shows widely different pressure effects among the different emission lines, which further vary with the surrounding gases used and also with the different ablation laser employed. It was found that most of the maximum emission intensities can be achieved in Ar gas plasma generated by ps laser at low gas pressure of around 5 Torr. This experimental condition is particularly useful for spectrochemical analysis of light elements such as H, C, and O, which are known to suffer from intensity diminution at higher gas pressures. Further measurements of the spatial distribution and time profiles of the emission intensities of H I 656.2 nm and Ca II 396.8 nm reveal the similar role of shock wave excitation for the emission in both ns and ps laser-induced plasmas, while an additional early spike is observed in the plasma generated by the ps laser. The suggested preference of Ar surrounding gas and ps laser was further demonstrated by outperforming the ns laser in their applications to depth profiling of the H emission intensity and offering the prospect for the development of three-dimensional analysis of a light element such as H and C.
authors.affiliation: Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD, Indonesia.
authors.forename: Syahrun Nur
authors.initials: SN
authors.lastname: Abdulmadjid
authors.forename: Nasrullah
authors.initials: N
authors.lastname: Idris
authors.forename: Alion Mangasi
authors.initials: AM
authors.lastname: Marpaung
authors.forename: Marincan
authors.initials: M
authors.lastname: Pardede
authors.forename: Eric
authors.initials: E
authors.lastname: Jobiliong
authors.forename: Rinda
authors.initials: R
authors.lastname: Hedwig
authors.forename: Maria Margaretha
authors.initials: MM
authors.lastname: Suliyanti
authors.forename: Muliadi
authors.initials: M
authors.lastname: Ramli
authors.forename: Heri
authors.initials: H
authors.lastname: Suyanto
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Kagawa
authors.forename: May On
authors.initials: MO
authors.lastname: Tjia
authors.forename: Zener Sukra
authors.initials: ZS
authors.lastname: Lie
authors.forename: Tjung Jie
authors.initials: TJ
authors.lastname: Lie
authors.forename: Hendrik Koo
authors.initials: HK
authors.lastname: Kurniawan