Degenerate four-wave mixing spectroscopy of ultrathin Au and Pt films

The results of experimental investigations of ultrathin (30 – 40 nm) metal Au and Pt films by means of picosecond degenerate four-wave mixing spectroscopy are presented. Within the model of nonlinear response formation, which takes into account the coherent superposition of contributions from many saturable interband transitions in the real spectrum of electronic states, the characteristic intraband relaxation times are determined to be 230 ± 30 fs and 180 ± 30 fs for Au and Pt films, respectively. The temperature of the electron subsystem is found to be 600 – 800 K.