A plasma self-confinement method induced by mutual extrusion of shock waves for liquid analysis of LIBS

To overcome the problems of poor plasma stability and low measurement repeatability caused by fluctuation and sputtering of liquid, a method called plasma self-confinement is proposed for liquid measurement by laser-induced breakdown spectroscopy (LIBS) in this work. With the help of shadow images, it was found that the liquid target could be returned to a calm state in a very short time, and the plasma back shock wave could be suppressed effectively. A quantitative analysis of the sodium chromate solution showed that the self-absorption could be reduced and the repeatability and sensitivity could be improved by plasma self-confinement mode LIBS when compared with liquid sheet mode LIBS. [Display omitted] •The plasma self-confinement mode for liquid analysis is proposed for the first time.•The sputtering and fluctuation of the liquid sheet are effectively suppressed, and the stability of the plasma is improved.•The self-absorption effect is reduced, and the repeatability and sensitivity for elements analysis in liquid are improved.