Effects of electron heating on femtosecond laser-induced coherent acoustic phonons

In this work, we employ a surface plasmon technique to resolve the dynamics of femtosecond laser-induced coherent acoustic phonons in noble metals. Clear acoustic oscillations are observed in our experiments. We further find that the initial phase decreases linearly with pump fluence. Our model calculations show that the hot electrons instantaneously excited by femtosecond pulses contributes to the generation of coherent acoustic phonons in metals.