Dynamics of laser-ablated particles from high T_c superconductor YBa₂Cu₃O_y

The dynamics of light-emitting particles produced by the excimer laser ablation of the high T_c superconductor YBa₂Cu ₃O_y has been investigated by means of space/time resolved optical measurements near the surface region with a space resolution of 100 μm and a time resolution of 0.1 ns. Two distinct components of ablated particles were observed: one with high average velocities over 5×10 ⁶ cm/s and the other with slow velocities, depending on laser energy density. The position of the maximum emission intensity in the slower component moved away from the surface and was further delayed from the time of maximum laser intensity as the laser energy density increased. If the incident laser was tilted from the normal of the target surface, the spatial distribution of the luminous plume inclined toward the incident laser beam. These results suggest that the slower component consists of light-emitting particles resulting from the fragmentation of clusters ejected from the surface.