Spectral-temporal characteristics of plasma induced by a nanosecond laser pulse at the sea water surface

Abstract

The investigational results on the dynamics of the spectra at laser break down at the sea water surface within a time interval of 0–30 µs are presented. The absorption lines of atomic hydrogen within 375–390 nm were recorded. To investigate the time dynamics of the intensity, the molecular bands of CN and OH were used, as well as the Na, Ca, and Mg resonance dublets; for the latter, the temporal dynamics of the ratio of line intensities to the background was studied. It has been shown that the time dependence of the ratio of line intensities (Na, Ca, Mg) to the background, the intensity of the continuous spectrum, and Na and Ca lines and molecular bands are approximated by the exponential dependence with two characteristic times, while the time dependence of the Ca line is approximated by the exponential dependence with one characteristic time.