Effect of hot electron kinetics on self-reflectivity of warm dense gold irradiated with femtosecond laser pulses

• DOI: 10.1016/j.apsusc.2021.150073
• Publication Date: 2021-05-13T15:30:54Z
• Authors: Minju Kim; Jae Hyung Jung; Seong Hyeok Yang; Min Sang Cho; Gyeongbo Kang; Gyusang Lee; Jong-Won Lee; Suhyeon Lee; Janghyeob Sohn; Byoung Ick Cho
• Keywords: DYNAMICS; HEAT-TRANSFER; 0103 physical sciences; ABSORPTION; COPPER; FILMS; 01 natural sciences; 7. Clean energy; TRANSPORT; TIME

Abstract Above the damage threshold of Au nanofoil, experimental and theoretical investigations of the fluence-dependent self-reflection of intense femtosecond laser pulses are presented. Measured reflectance shows not only the fluence-dependency, but also the laser pulse duration dependency, which is barely described by the calculation of dielectric function of high-temperature Au, based on the traditional two-temperature model. A simple hot electron kinetic model, which contains a nonthermalized electronic subsystem cooperated with the two-temperature model, is considered to determine transient electron densities and temperature to calculate the dielectric functions and self-reflection of femtosecond laser pulses. Comparison to experimental data shows the effect of hot electrons with a relaxation time of a few hundreds of femtoseconds on the transient optical properties of gold under a strong excitation.