THE THEORY OF PS AND SUB-PS LASER-PULSE INTERACTION WITH METALS - II - SPATIAL TEMPERATURE DISTRIBUTION

The interaction of short laser pulses with metals is described in term s of a new model involving a generalised nonlocal heat flow in time. T he resulting system of coupled differential equations contains additio nal terms that originate in the thermal inertia of the electron subsys tem. They are connected to the time derivative of both the laser inten sity and the coupling of the electrons to the phonons. After briefly d iscussing the importance of the coefficient of heat exchange and of th e different contributions to its main parts, the electron-phonon coupl ing and the average of the squared phonon frequencies, we present snap -shot-like calculations of the spatial temperature distribution along the z-axis for Al, Au, Pb and Nb for different intensities but fixed p ulse duration tau(L) = 250 fs. In addition, the electron and phonon te mperatures inside a thin Au film are studied in detail. Our results ar e compared to those arising from a standard two temperature model (TTM ) and those of the conventional theory. While the traditional theory b ecomes invalid in most cases at least in the ps-range the differences between our approach and the TTM become the more pronounced the smalle r the coefficient of heat exchange. (C) 1998 Elsevier Science B.V.