Can pulsed laser excitation of surfaces be described by a thermal model?

In using pulsed laser excitation of surfaces to induce desorption or reaction of adsorbed molecules, it has generally been assumed that the absorbed energy is rapidly randomized, and a thermal model can be used to calculate the surface-temperature change. In this work, the transient temperature jump on a Ag(110) surface induced by an 8-nsec laser pulse is directly monitored with a psec probe pulse. The probe is based on a temperature-dependent second-harmonic-generation effect. The experiment provides the first direct evidence that the heat-diffusion model can correctly predict the magnitude and the time evolution of the temperature on the surface. (Author)