Spectroscopic characterization of laser-ablated manganese sulfate plasma M. SALIK, 1 M. HANIF, 2 J. WANG, 1 AND X. Q. ZHANG 1 1 School of Science, Beijing Jiaotong University, Beijing, China 2 MCS, National University of Sciences &Technology, Rawalpindi, Pakistan (RECEIVED 4 August 2013; ACCEPTED 5 January 2014) Abstract In this work, we present the spectroscopic studies of the plasma generated at the surface of manganese sulfate by the fundamental (1064 nm) and second harmonic (532 nm) of a Q-switched Nd:YAG laser. The 4s4p 4 F 7/2 → 4s 2 H 9/2 at 438.80 nm, 4p 2 I 11/2 → 4s 22 I 11/2 at 440.80 nm, 4p 4 G 11/2 → 4s 2 H 9/2 at 464.27 nm, 4p 4 F 5/2 → 4s 4 D 7/2 at 467.16, 4p 4 F 5/2 → 4s 24 G 7/2 at 515.08 nm, and 4p 4 F 7/2 → 4s 24 G 9/2 at 519.65 nm transitions have been used to estimate the electron temperature through the Boltzmann plot method. The number density has been estimated from the Stark broadened profiles of the spectral line 348.30 nm. The spatial behavior of the electron temperature and number density has been examined at different ambient air pressures and with laser irradiance. The temperature and number density are found to be in the range from 9842 K to 9371 K and 1.58 × 10 17 to 3.26 × 10 16 cm -3 for the 1064 nm laser, from 9668 to 9297 K and 2.27 × 10 17 to 5.79 × 10 16 cm -3 for the 532 nm laser. Keywords: Electron density; Laser ablation; Manganese plasma; Optical emission spectroscopy; Plasma temperature 1. INTRODUCTION Laser induced breakdown spectroscopy (LIBS) is an analyti- cal technique, which was first reported in early 1960s and has been reviewed by several researchers. This sensitive tech- nique is based on optical detection of certain atomic and mol- ecular species by monitoring their emission signals from the laser induced plasma. It provides a useful method to deter- mine the chemical composition of a wide range of materials including metals, liquids, aerosols, plastics, minerals, and biological tissues, etc. (Miziolek et al., 2006; Cremers & Radziemski, 2006; Singh & Thakur, 2007). It is a simple analytical technique as compared to many other types of elemental analysis because of its straightforward experimen- tal set-up. In this technique, one requires a pulsed laser for generating micro-plasma on the target surface and elemental analysis is accomplished by studying the emission of the plasma plume. The laser induced plasma characteristics depend upon several parameters, which include the features of the target, properties of the ambient medium, laser wave- length, and pulse duration etc. The first direct spectral analy- sis made by LIBS can be attributed to Pasquini et al.(2007) and Rung and Minck (1964). However, in the 1980s, this technique is in continual increase as an analytical instrument in research (Rusak et al., 1998). Manganese sulfate (MnSo 4 ) is an important chemical compound. Its constituent elements are manganese, sulfur, and oxygen. Basically, it can be identified as a colorless, odorless, solid substance. This naturally occurring mineral is mostly found in hydrated state. MnSo 4 has a number of medical as well as non-medical uses. Due to its importance and wide utility, it remained a subject of interest for many re- searchers. Sun et al.(2000) have studied the determination of Mn and Si in iron ore by Laser-induced plasma spectroscopy. Horiba et al. (2004) studied the In situ Mn 2p-3d resonant photoemission study on La 0.6 Sr 0 . 4 MnO 3 epitaxial thin films grown by laser MBE. Hakola et al. (2004) reported the Ni-Mn-Ga films on Si, GaAs and Ni-Mn-Ga single crys- tals by pulsed laser deposition. Dhananjay et al. (2006) pre- sented dc and ac transport properties of Mn-doped ZnO thin films grown by pulsed laser ablation. Measurement of stark broadening of Mn I and Mn II spectral lines in plasmas used for laser-induced breakdown spectroscopy was studied by Bredice et al. (2007). Tawfik and Mohamed (2008) studied the improved LIBS limit of detection of Be, Mg, Si, Mn, Fe, and Cu in aluminum alloy samples using a por- table echelle spectrometer with ICCD camera. Dongxia et al. 137 Address correspondence and reprint requests to: M. Salik, School of Science, Beijing Jiaotong University, Beijing, China 100044. E-mail: salikqau@yahoo.com Laser and Particle Beams (2014), 32, 137–144. © Cambridge University Press, 2014 0263-0346/14 $20.00 doi:10.1017/S0263034614000020