The interaction of 32.5 and 6 nm ultrashort X-ray pulses with the solid materials B4C, SiC and Si is simulated with a non-local thermodynamic equilibrium (NLTE) radiation transfer code. We study the ionization dynamics as function of depth in the mat
erial, modifications of the opacity during irradiation and estimate crater depth. Furthermore, we compare the estimated crater depth with experimental data, for fluences up to 2.2 J/cm2. Our results show that at 32.5 nm irradiation, the opacity changes with less than a factor of 2 for B4C and Si and a factor of 3 for SiC, for fluences up to 200 J/cm2. At a laser wavelength of 6 nm, the model predicts a dramatic decrease in opacity due to the weak inverse bremsstrahlung, increasing the crater depth for high fluences.
