Analyses of heavy metals by soil using dual-pulsed laser induced breakdown spectroscopy

Abstract

The heavy metal elements contained in soil samples which are collected from Changchun train station, CUST campus, South Lake and Jingyue Lake park are separately analyzed by using the orthogonal dual laser pulses induced breakdown spectroscopy (DP-LIBS). The elements Mn, Cr, Cu and Pb are qualitatively analyzed according to the LIBS spectral intensity. It is shown that the intensity of the spectrum is greatly enhanced by using the DP-LIBS and the enhancement is closely related to the delay time between the double pulses. Enhancement variation with delay time presents double-peak changing when 532 nm and 1064 nm laser pulse energies are 70 mJ and 100 mJ respectively. The enhancement of Mn I 406.4 nm is 2.75 at a delay time of 20 s and it is 2.4 at a delay time of 30 s when the second peak appears. The enhancement mechanism of orthogonal pre-ablation DP-LIBS is further discussed.