Thermal diffusivity measurements of sub-micron organic dye thin films using a high temperature superconductor bolometer

The thermal diffusivity of a thin organic dye layer deposited atop thin fil ms of the high temperature superconductor YBa2Cu3O7-delta is measured using a pulsed laser flash method. Here, the underlying superconductor acts as a highly sensitive temperature transducer after appropriate conversion of th e transient voltage response from 7 ns optical pulses. Film surface tempera ture decays for several thicknesses of the dye layers were evaluated; these decays exhibited a linear dependence of the time at half temperature maxim um versus thickness squared. Three dimensional finite difference modeling w as used to study and extract the thermal diffusivity values of the thin org anic layers as well as to investigate the transient temperature distributio ns within the dye and superconductor areas. (C) 1998 American Institute of Physics. [S0003-6951(98)01145-0].