Observation of the light emitting region produced by pulsed laser irradiation to a solid–liquid interface

Imaging of the light emitting region produced by pulsed laser irradiation to a graphite–water interface was performed at various time delays after the pulse. The duration of the light emission was about 100 ns, which was much shorter than that in air (more than 1000 ns). The lateral size of the light emitting region measured by half-maximum intensity was about 0.15 mm and was almost constant within the time range of the observation, i.e., 21–100 ns. Also the size was one-tenth of the maximum size obtained in air. The density and the pressure of this region were estimated from the amount of ejected carbon species and the size of the expansion volume. The results give us important informations for understanding the covering effect of water upon the expansion of the ejected species.