Laser shortpulse heating of metallic substrates requires microscopic examination of the energy transport in the irradiated region. This is because of low specific heat capacity of electrons, which results in nonequilibrium temperature distribution in this region. In the present study, laser shortpulse heating of gold with variable properties is considered. Nonequilibrium energy transport is modelled using an electron kinetic theory approach. The resulting integro-differential equations are reduced to partial differential equation using a Fourier transform method. The resulting differential equation is further transformed into two differential equations similar to those given in the two-equation model. The coefficients of the differential equations are correlated. It is found that variable properties results in higher lattice site and lower electron temperatures as compared to those corresponding to constant properties case.
Laser short-pulse heating of silicon film is considered and effect of the spatial distribution of absorption coefficient on electron and lattice site temperatures is examined. The high absorption region in the silicon film resembles the presence of absorbed particles in this region, since the absorption coefficient of silicon at the wavelength of the laser irradiation is significantly low. Electron and lattice temperatures are predicted using the electron kinetic theory approach. Three different spatial distributions of absorption coefficient are considered in the simulations. It is found that electron temperature attains the highest for the case of high absorption coefficient located in the surface region of the silicon film. As the high absorption region moves inside the film, electron and lattice temperatures become low.
We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero.