The interaction of multiply charged ions with solid surfaces can induce strong and localized electronic excitations as a result of charge exchange. While ultimately these exciations can be used for material modifications on the atomic scale through electronic sputtering, the susceptibility of a surface to this type of nanoscale machining is determined by the local surface response to strong excitations. Probing the nanoscale charge dynamics on a femtosecond timescale is challenging, but using promptly emitted (messenger) electrons from the ion impact on a freestanding 2D material in coincidence with the transmitted ion finally allows a detailed insight on how long an induced surface charge stays confined.