Time-integrated and time-resolved VUV LIBS: a comparative study

Abstract

Laser Induced Breakdown Spectroscopy (LIBS) is an analytical technique, used to classify and potentially quantify elements in complex hosts (or matrices). Vacuum Ultraviolet Laser Induced breakdown Spectroscopy (VUV LIBS) can offer potential improvements in detection of light elements in bulk metals over traditional LIBS in the visible region. This is due to presence of an abundance of resonance transitions at shorter wavelengths. This extends the ability to discriminate between the emission from different elements, particularly light elements such as carbon, sulfur, lithium, beryllium etc. Additionally, the precision of LIBS is limited by the continuum emission at the early stage of the plasma lifetime. The performance of LIBS can be improved by using a time resolved detection system [5], reducing the contribution from the continuum. In this study, the detection of the carbon content in steel samples is performed by time- integrated and time-resolved VUV LIBS. The experimental setup consists of a dual pulse system with Nd:YAG laser (1064 nm, up to 450 mJ, pulse duration 6 ns) used to irradiate the samples, a vacuum system to prevent absorption of the VUV radiations and a VUV spectrometer to collect and measure the emission spectra. Samples of four different concentrations of carbon in steel are used for the study. The resultant time integrated LIBS limit of detection and signal to background ratio is compared with time resolved VUV measurements.