TRANSPORT OF YO MOLECULES PRODUCED BY ARF LASER-ABLATION OF YBA2CU3O7-DELTA IN AMBIENT OXYGEN GAS

One-dimensional-imaging laser-induced fluorescence spectroscopy (1D-LI F) has been applied to investigate the dynamics of the nonemissive neu tral particles (YO molecules) during the ArF excimer laser ablation of YBa2Cu3O7-delta in an ambient oxygen gas. Investigating the ID-LIF ob servation, the propagation.of particles through the ambient gas at app ropriately high pressures is categorized into two phases, the propagat ion phase and the diffusion phase. In the propagation phase, the point source blast wave model (shock model) describes well the dynamics at high background gas pressures. Particles propagate according to the sh ock model over a finite distance from the pellet surface after the abl ation, and almost stop there. The propagation distance depends on the ambient gas pressure and the ablation fluence. After the propagation c eases, the particles start to diffuse through the background gas; that is the diffusion phase. Rotational temperature variations of YO molec ules in the different phases are also measured. Rotational temperature s as high as 1000 K are observed even in the diffusion phase.