Emission enhancement using two orthogonal targets in double pulse laser-induced breakdown spectroscopy

The enhancement of emission intensity resulting from the interaction between two laser-induced plasmas on two orthogonal targets was investigated using double pulse laser-induced breakdown spectroscopy (LIBS) at 0.7 Pa. by means of time-resolved spectroscopy and fast photography. The results showed that the interaction between both plasmas improved carbon emission intensity in comparison to a single laser-induced plasma. For all the carbon lines of interest 477.2 nm (CI). 426.7 nm (CII), and 473.4 nm (C-2 Swan band head). the intensity enhancement showed a maximum at a delay between lasers in the range from 2 to 5 mu s: moreover it increased with the fluence of the first laser. On the other hand, in the case of C-2 the intensity enhancement reached a maximum at 5 mm from the target: however it decreased with increasing fluence of the second laser. The largest intensity enhancement found was twofold for atomic species and sixfold for molecular species. (C) 2009 Elsevier B.V. All rights reserved.