Influence of laser energy and accumulation number on the spectral characteristics

An experimental setup was established by a Nd:YAG laser operating at 1064 nm and a grating spectrometer with intensity charged couple device (ICCD) detector. Influence of laser energy and accumulation number on measurement by laser-induced breakdown spectrometry (LIBS) was investigated. The typical spectrum lines of heavy metal elements Cr (425.43 nm) in soil was chosen and identified. The experimental results showed that with the laser energy range from 40 mJ to 200 mJ the intensity of the spectrum line increased and the signal to background ratio (SBR) first increased, then decreased, when the laser energy reached 110 mJ, SBR was optimal. The minimum of the relative standard deviation (RSD) was obtained when the accumulation number was 40. In this experiment the best value of RSD is 4.49%. From these results, it was found that the propertites of the laser plasma depend on the laser energy and accumulation number.