One-dimensional-imaging laser-induced fluorescence spectroscopy (1D-LIF) has been applied to investigate the dynamics of the nonemissive neutral particles (YO molecules) during the ArF excimer laser ablation of YBa2Cu3O7−δ in an ambient oxygen gas. Investigating the 1D-LIF observation, the propagation of particles through the ambient gas at appropriately high pressures is categorized into two phases, the propagation 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 shock model over a finite distance from the pellet surface after the ablation, and almost stop there. The propagation distance depends on the ambient gas pressure and the ablation fluence. After the propagation ceases, the particles start to diffuse through the background gas; that is the diffusion phase. Rotational temperature variations of YO molecules in the different phases are also measured. Rotational temperatures as high as 1000 K are observed even in the diffusion phase.

Two-dimensional laser-induced fluorescence spectroscopy has been applied to visualize the behavior of non-emissive species in pulsed-laser deposition process of YBa2Cu3O7−x. Behavior of Ba atoms at different oxygen gas pressures and near the substrate is presented. Based on this observation, oxidation of Ba atoms is discussed. The distributions of BaO molecules are also shown and compared with those of Ba atoms.

Effects of cumulative ablation on the ejection of particulates and molecular species in pulsed-laser deposition are studied by Mie scattering and laser-induced fluorescence spectroscopy, respectively. When a fresh target is ablated, a large amount of particulates are ejected during several initial shots and rapidly decreased within the first ten shots of ablation. This is due to the ejection of powder residues which are struck on the target surface during the polishing process. After this period, ejection of particulates increased gradually and almost saturated after 200 shots. The saturation characteristic is empirically formulated as a function of the number of cumulative ablations. On the other hand, ejection of molecular species rapidly decreases during the initial 500 ablations and afterwards decreases more slowly with further ablation. The effects of cumulative ablation on the particle ejection are discussed in conjunction with the structural modification of the ablated surface observed by the scanning electron microscope.

The interaction between a substrate and an expanding plume, which is produced in a pulsed-laser deposition process of high-temperature superconducting thin films, has been investigated by observing one-dimensional laser-induced fluorescence images of ablated yttrium oxide molecules. The results show the importance of fluid-like interactions of the ablated particles with the substrate. In relatively high oxygen pressure, it is found that the ablated particles are reflected and stagnate in front of the substrate, and are then transported by diffusion onto the substrate.

The scattering of Ba atoms produced from an ArF laser ablated YBa2Cu3O7−δ target on a Si substrate was directly observed by laser induced fluorescence spectroscopy. A gated diode array determined the spatial and the time of flight (TOF) distributions of the scattered Ba atoms on the substrate. It is shown that a sticking coefficient of Ba atoms was less than unity and Ba atoms were scattered roughly isotropically. The velocity of the scattered atoms is estimated from the TOF distribution.