VUV laser-induced plasma emissions for ultra-micro spectrochemical analysis of liquid samples

The specific case of pulsed-laser ablation of liquid samples were studied and the production mechanism of the plasma emissions aimed to reduce their interfering effects. Aqueous solutions seeded with various metal salts as test analysis were ablated with laser pulses of 532-nm, 248-nm, and 193-nm wavelengths. Time and space resolved spectra of the plume emissions were analyzed to yield estimates of plasma temperature and electron density. With 532-nm ablation, the plasma produced was hot and extensively ionized, with electron density in the 10¹⁸ cm^-3 range. 193-nm laser ablation at similar fluence generated plasmas of much lower temperature but comparable electron density.