Metal oxide absorption coefficients for use in intense laser interaction with solids

Abstract

The existence of metal oxides at the surface of a metal irradiated by an intense laser beam leads to partial absorption of the incident radiation in the blow-off vapor due to vibration-rotation bands which exist in the vicinity of the laser frequency. We present calculations for the vibration-rotation bands of SiO, FeO, AlO, and TiO in the 10.6-μ range for application to CO2 laser interaction. The absorption coefficients are calculated by use of a just overlapping line model. The range of validity of the model is established by performing line-by-line calculations in the vicinity of a typical laser line. The absorption coefficients are then supplemented with an equilibrium chemistry model for laser interaction with Al2O3 and SiO2 surfaces. These calculations may be used to establish the importance of surface shielding for cases in which the blow-off vapor exists in the range of temperatures up to about 7000°K.