Rotational spectra and temperature evaluation of C2 molecules produced by pulsed laser irradiation to a graphite–water interface

Abstract

Temperature of an ablation plume produced by pulsed laser irradiation to a graphite target submerged in water was evaluated as a function of time by analyzing the emission spectra of C2 molecules. The method is based on the determination of rotational temperature from the rotational spectra of the (0,0) Swan band of C2 molecules. In the time range shorter than 1000 ns from the ablation laser pulse, the rotational temperature of ∼6000 K was obtained. After 1000 ns it decreases rapidly, in contrast to the temperature obtained for the irradiation in air, where the decrease of the temperature is rather slow. The linewidth obtained as one of the fitting parameters suggests the high density and high pressure of this region. Temporal behavior of the laser ablation plume in water is discussed.