Time averaged emission spectra of Nd:YAG laser induced carbon plasmas

Laser-induced breakdown carbon plasma emission spectroscopy (LIBS) experiments were carried out using a Nd:YAG laser and a graphite target. Spectra were collected in time-averaged fashion and are discussed in terms of atomic and molecular composition. The vibration-rotation temperature of the Swan transitions of the C-2 radical in the plasma was determined using least-squares fitting to accurate theoretical spectra. Electron density and electron kinetic energy estimates were also obtained on the basis of the line width and relative intensity of singly and doubly ionized carbon lines. Throughout the treatment local thermodynamic equilibrium (LTE) and an optically thin plasma were assumed. The effects of added helium and CO2 background gases on the carbon plasma are discussed. Features attributable to the C-3 radical are difficult to detect in our spectra. (C) 2003 Elsevier B.V. All rights reserved.