PICOSECOND ACOUSTIC MEASUREMENTS OF LONGITUDINAL WAVE VELOCITY OF SUBMICRON POLYMER FILMS

摘要: We apply picosecond acoustic techniques to determine the longitudinal wave speed of submicron polymer films in through‐thickness dimension. The time‐of‐flight an elastic propagating through film is measured using optical pump/probe technique. poly(methyl methacrylate) thickness ranging from 20 130 nm has been determined. A pronounced increase observed for less than 40 nm.