Laser ablation at solid-liquid interfaces: An approach from optical emission spectra

The emission spectra from the solid-liquid interface irradiated by a pulsed laser were studied. The solid target used in this study was graphite and b oron nitride, and the liquid in which the target was immersed was water, be nzene, n-hexane, and carbon tetrachloride. The results showed strong contin uous spectrum immediately after a pulse shot, whereas after approximate to 100 ns later from the irradiation it was greatly reduced, and instead, the emission from small molecules dominated the spectra. The line spectra of sm all molecules observed in the later time range indicate the chemical reacti on between the ablated species and the species originated from the liquid m olecules. The intensity of the continuous spectrum was very prominent compa red to what has been observed for solid-gas interfaces. This is due to rapi d electron ion recombination or bremsstrahlung due to highly confined inter face plasma. (C) 2000 American Institute of Physics. [S0021-9606(00)70619-2 ].