Characteristic decay times of continuum and emission doublet intensities (Mg II 279.6 and 280.3, Ca II 393.4 and 396.8, Na I 589 and 590.6 nm) are presented. Measurements were made for plasma induced by 42 fs laser pulse within time interval 0÷85 ns. It is shown that Na I doublet intensity is described by monoexponential dependence over the whole observation time interval. Evaluation of electron density, which changes from 3.0 •1016 to 2.4 •1015 cm-3, was made using triple recombination coefficient. Validity of local thermodynamic equilibrium criterion and dependence of line-to-background ratio on gate delay is investigated.
laser-induced breakdown spectroscopy, femtosecond laser pulse, breakdown, sea water, recombination