Enhanced Laser Induced Break-down Spectroscopy

Laser induced break-down with/without a supplementary RF discharge excitation was investigated by means of optical emission spectroscopy. Calibration free method in LIBS for determination of concentrations in sample has problems with self-absorption of emission lines. This could lead to incorrect determination of concentration of electrons. Electron temperature is used to determine concentration of examined elements in sample. Atoms and radicals ablated from the Cu target and excitated by laser beam are further re-excitated by RF discharge in order to prolong their life-time. Laser induces break-down spectra of copper sample under argon atmosphere at pressure of 380 Pa were measured and electron temperatures from Boltzmann plot using argon and/or copper neutral lines were deduced. The results for two different experimental conditions (delay of spectra recording 1 s and 200 s after laser shot) were compared. After 200 s delay no influence of laser induced breakdown presence on RF discharge spectra was observed. The results from laser induced break-down and additional RF discharge excitation were compared.