INVERSE ANALYSIS FOR ESTIMATING THE ELECTRON-PHONON COUPLING FACTOR IN THIN METAL-FILMS

The electron-phonon coupling factor controls the heat transfer between electrons and lattice when thin metal films are heated by laser pulse s with duration of order of femtoseconds. An inverse analysis is used to estimate this factor from transient measurements of the normalized variation of reflectivity and transmissivity of the metal film. The se nsitivity coefficients are examined in order to determine the optimum time interval for the measurements. Results obtained with simulated me asurements containing random errors show that the inverse analysis pro vides accurate estimates for the electron-phonon coupling factor. A st atistical analysis is performed for the evaluation of the confidence i nterval for the estimates. Actual experimental data of reflectivity an d transmissivity available in the literature are used to estimate the electron-phonon coupling factor for films of gold and copper. (C) 1995 American Institute of Physics.