Morphology dependent ultrafast electron dynamics in ultrathin gold films

Ultrafast electron dynamics in 5 nm thick gold films have been investigated as a function of film morphology. The transient reflectivity data reveal a sub-100 fs rise time and a complex relaxation profile on the picosecond timescale. These data are discussed in terms of a modified two-temperature model of the electron dynamics accounting for the initial relaxation of the non-thermal population. The electron-phonon coupling may be sensitive to film morphology. The possible origin of this behaviour is discussed and results are placed in the context of enhanced photochemistry on thin metal films.