Moisture Measurement Using LIBS

LIBS is traditionally an atomic emission spectroscopy involving sampling, atomization and excitation of a sample by laser ablation. The radiative cooling of the created plasma is spectrally analyzed to provide the elemental composition of a sample of interest. In 1962, two years after the invention of the laser, Jarrell Ash Co. developed the Laser Microprobe that revolutionized the elemental microanalysis by the concept of laser ablation and crossexcitation by electrodes, which was the precursor of LIBS. One year later, Debras-Guédon and Liodec [1] demonstrated the independent use of the laser to perform spectral analysis of a large panel of materials. Since then, LIBS still relies on this procedure and instrumentation: a laser pulse from which energy is focused on a sample to create the plasma, and optics to transport the optical emission of the plasma to the spectral analyzer, usually a spectrometer with a detector array (Fig. 1). Such a simple apparatus is attractive to researchers and end-users in many fields where direct access to the sample is difficult, the sample preparation (gas, liquid, solid or aerosols) is not possible or too complicated, or the analysis requires high speed: forensic science, homeland security, geology, on-line material characterization, space exploration, etc..