Confinement of Laser Plasma by Shock Waves for Increasing Signal Intensity in Spectrochemical Determination of Trace Elements in Ores

We have studied the confinement of laser plasma by shock waves (also known as spatial confinement induced on an ore sample, as exemplified by changes in the intensity of Ag I 328.07 nm and Au I 267.60 nm emission lines. It is established that the maximum increase in intensity of these lines is observed at 2- to 2.5-mu s delay, which corresponds to an increase in the plasma temperature up to 5900 K. The signal-to-noise ratio upon the spatial confinement of plasma is somewhat reduced, but the overall growth of signal intensity provides increase in the sensitivity of laser-induced breakdown spectrometry for determining trace elements in ores.