Thermalization of a UV laser ablation plume in a background gas: From a directed to a diffusionlike flow

Abstract

Combined diagnostic measurements of deposition rates and ion time-of-flight signals have been employed to study the expansion of a laser ablation plume into a background gas. With increasing gas pressure the angular distribution of the collected ablated atoms becomes broader, while the total collected yield decreases. The total collected yield shows three separate regimes with increasing pressure, a vacuumlike regime, a transition regime with increasing plume broadening and splitting of the ion signal, and at the highest pressure a diffusionlike regime with a broad angular distribution. In the high-pressure regime the expansion can be described by a simple model based on diffusion from a confined plume.

The influence of plasma dynamics on the growth of Sm0.55Nd0.45NiO3 solid solution during pulsed laser deposition

“…The drag model fits very well our experimental data at later time delays for all the used oxygen pressure. According to Amoruso et al [30,34,35] and J. Schou [36] the plume stops when the shockwave gradually degenerates into a sound wave in the undisturbed gas, and almost all the energy initially stored in the plume is converted into a sound wave propagating in the ambient gas. In Table 1 shock-wave-like expansion and finally the plume stopping.…”

Pulsed laser ablation of complex oxides: The role of congruent ablation and preferential scattering for the film stoichiometry

“…In this case, the plume species can reach the substrate only through diffusion into the background gas. 24 In such a regime, the diffusion-like flow of the plume species towards the substrate can be significantly non-stoichiometric as a consequence of the collisional processes between ablated species and background gas molecules. 15 On the contrary, an increase of the laser fluence progressively reduces the background gas confinement, and the plume impacts on the substrate at earlier times (see Fig.…”

Influence of the oxidation state of SrTiO3 plasmas for stoichiometric growth of pulsed laser deposition films identified by laser induced fluorescence

“…7 Argon and oxygen have a similar atomic weight and PLD plasmas exhibit very similar expansion dynamics in either Ar or O 2 . 9 By mixing Ar and O 2 , we maintain a constant total pressure in all measurements with comparable gas dynamic processes, such as expansion, propagation speed, and collision rates, for all gas mixtures. As the ablation laser fluence is kept constant for all measurements, changes in plasma composition will be primarily caused by a change in chemical processes and not by changing dynamics.…”