Probing the ultrafast electron and lattice dynamics of gold using femtosecond mid-infrared pulses

We study the ultrafast electron and lattice dynamics of thin gold films with mid-infrared transmission and reflection pump-probe spectroscopy. We determine the time dependence of the dielectric function, which yields the electron-phonon coupling constant $G$ that determines the energy exchange rate between the electrons and the lattice. From the experimentally obtained dielectric function, we determine the dependence of the electron-electron and the electron-lattice scattering rates on the electron and the lattice temperature.