Spectroscopic energy characterization of laser-induced titanium plume

TLDR: In this paper, a titanium target was ablated by a KrF excimer laser with fluences varying from 4 to 8 J/cm2 in an argon-filled environment with pressures ranging from vacuum to 1 torr.

Abstract: A titanium target was ablated by a KrF excimer laser with fluences varying from 4 to 8 J/cm2 in an argon-filled environment with pressures ranging from vacuum to 1 torr. The effects of laser fluence and background gas pressure on the kinetic energies of the ablated species were investigated by temporally and spatially resolved emission spectroscopy. The maximum surface temperatures were calculated by an one-dimensional conduction model. Experimentally obtained surface temperatures from the kinetic energy of the ejected plume were one order of magnitude higher than the calculated temperatures. This discrepancy is most likely due to the absorption of laser energy by the plasma that is formed early in the pulse. Temporally resolved imaging with 10-ns gate width was also employed to reveal the evolution of the ablated plume against the background gas. Separation of slower and faster components were observed for pressures above 50 mtorr, and angular concentration of titanium in the plume was determined.