Temperature Dependence of Pressure Sensitive Paints

The photoluminescence properties of a typical pressure sensitive paint (PSP) formulation consisting of tris-(4,7-diphenylphenanthrollne)ruthenium(II) dichloride (RudpCl) dispersed in a polydimethylsiloxane (PDMS) binder were examined as a function of temperature. Thus, the temperature dependence of the luminescence intensity I em and emission decay lifetime τ em of the PSP formulation and for the photoluminescent RudpCl dye dissolved in ethanol solvent were determined for temperatures ranging from 5 to 50°C. Analysis of the experimental data indicates that under deoxygenated conditions the temperature dependence of I em and τ em for either the PSP formulation or ethanol solutions is dominated be the intrinsic temperature dependence of the nonradiative decay rate of the photoluminescent dye molecule. By contrast, for the PSP formulation at 1-atm air pressure the temperature dependence of I em and τ em is dominated by the temperature dependence of the diflusivity of oxygen in the PDMS binder. The implications of the experimental results on the design and application of PSP formulations are discussed.