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.