Enhanced laser-induced plasma spectroscopy (LIPS) by second-pulse selective wavelength excitation

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There is always a great need in industry for technologies that allow rapid, fast and in-situ chemical analysis at, if possible, low cost. Over recent years, the Laser-Induced Plasma Spectroscopy (LIPS) technique has become an important tool for real-time spectrochemical analysis of a wide variety of materials. In conventional LIPS, a moderately powerful laser pulse is focused onto a target material to expel a small amount of hot and bright matter (a plasma) from the impact site. The radiation emitted from this plasma is then analyzed by means of a spectrometer for qualitative and quantitative purposes. The LIPS technique has many striking advantages over the other existing techniques, since no sample preparation is required, and it allows remote and in-situ real time analysis. However, these advantages are currently outweighed by a poorer sensitivity than for the more cumbersome conventional analytical techniques for the detection of trace elements. The objective of this project is to increase substantially the sensitivity of the LIPS technique. For that purpose, we propose to use basically two laser pulses instead of only one as in conventional LIPS. The first pulse generates the plasma and the second pulse resonantly excites a specific quantum level of a given atomic species inside the plasma. The effect of this second laser pulse is to increase the emission of the atomic species of interest for an easier detection. In the framework of this general scheme we also propose to investigate the use of very short excitation pulses in order to allow a better contrast of the detected signal with the background radiation. The project involves collaborators from a university (INRS) and a government laboratory (NRC-IMI) who have been working actively on LIPS together for several years, as well as three Canadian companies (INCO, Pharma Laser, and Scintrex Trace) of wide industrial interest. Since these companies are already involved in short-term implementation of LIPS, in collaboration with NRC-IMI, this project appear to them as an opportunity to apply the LIPS technique on a much larger scale than expected initially.