Tetsuo Sakka

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 boron nitride, and the liquid in which the target was immersed was water, benzene, n-hexane, and carbon tetrachloride. The results showed strong continuous spectrum immediately after a pulse shot, whereas after ≈100 ns later from the irradiation it was greatly reduced, and instead, the emission from small molecules dominated the spectra. The line sp

The effect of pulse duration upon the line profile of Cu I emission observed by laser ablation of a copper metal plate immersed in water has been examined. By irradiating a pulse with the duration longer than 40 ns the spectral profile with clear narrow emission lines of Cu atoms is obtained, while the emission spectra always suffer from broadening and self-absorption by the irradiation of the 20 ns pulse for the ablation. The results show that the use of a long-duration pulse enables in situ el

We propose a method for determining the spatial distribution of population densities for the species in laser-produced plasma. Our method relies on the parameter fittings of the experimentally observed self-reversed emission profiles to the model which is based on the calculation of one-dimensional radiative transfer. Employed parameters in the model represent spatial distribution of emitters, absorbers, and plasma free electrons. Since the density of plasma electrons has a spatial dependence, S

A light emission from aluminium atoms produced by a pulsed laser irradiation to the aluminium metal-water interface was studied by emission spectra and analysed on the basis of a rate model. The time dependence of the emission spectra was obtained from the 20-80 ns time range. Early in this time range the Al (2P°-2S) transition appears as an absorption line in a continuous spectrum, suggesting that the optical thickness of the light-emitting region is considerably high and that aluminium atoms p