Fundamentals to applications of underwater laser-induced breakdown spectroscopy (LIBS) of submerged solid targets are reviewed. Since the deformation of spectral lines caused by plasma confinement has been the most serious problem in underwater LIBS, the methods developed to overcome this effect are overviewed. Deep-sea LIBS, which is the most successful application of underwater LIBS, is described in some detail as well as the hydrostatic pressure effects. Since the downsizing of underwater LIBS instrument is an important task for the applications to on-site measurements, studies on non-gated LIBS are covered. In the subsequent section, the methods for the quantitative analysis of the underwater LIBS signal are reviewed. The basics of the plasma parameters used in quantitative analysis are explained, and various methods of quantitative analysis applicable to underwater LIBS are described.
Keywords: LIBS; elemental analysis; laser plasma; pulsed laser ablation in liquid; quantitative spectral analysis; underwater laser-induced breakdown spectroscopy.