Kinetics of subnanometer displacements of solid surfaces under local heating by a laser pulse

A method with space-time resolution Δr～ µm and δt～0.1 µs is proposed for investigating the kinetics of angstrom-size displacements and deformations induced on solid surfaces by local irradiation with a laser pulse. The instantaneous deformation profiles were recorded at a set of points on the surface on micron-size scales by the method of photothermal deformation of the surface (PTDS) according to the kinetics of the deflection of a probe laser beam followed by extraction of data corresponding to the same moment in time; the instantaneous displacement profiles were obtained by integrating the instantaneous deformation profiles numerically in the radial direction. Instantaneous profiles obtained in this manner for angstrom-scale deformations and displacements are presented for a number of metal samples. The nature of the kinetic displacements obtained at the center of an ～10–100 µm heating laser spot is discussed.