Thermal Diffusivity Measurement for Titanium Thin Films on Copper Substrate by Laser Produced Plasmas

The transport properties of condensed phase materials are, in principle, dependent on the local structure and composition of the specimen. This is particularly evident near the free surface of a solid alloy specimen where the morphology, composition, and thermal diffusivity exhibit significant depth dependence, as demonstrated in an earlier study of the depth-resolved thermal diffusivity of a galvanized steel specimen. A new non-contact method was used, based on timeresolved, spectroscopic measurement of the total mass removed from the specimen surface representatively in elemental composition by a high-power laser pulse. A new study of a titanium thin film of varying thickness deposited on a copper substrate is preseInted. The titanium thin film is first fabricated in a vacuum and then immediately analyzed for composition and thermophysical properties in situ, both by the method of representative laser-produced plasmas (LPP). Successive ablation layers of the thin film, as exposed by LPP ablation, have revealed the dependence of the thermophysical properties on film thickness as well as on depth. The existence of a characteristic length over which the substrate influences the dynamics of thermal transport in the titanium thin film has also been observed.