Composition-dependent electronic energy relaxation dynamics of metal domains as revealed by bimetallic Au144−xAgx(SC8H9)60 monolayer-protected clusters

We examined the electronic relaxation dynamics for mono and bimetallic Au 144− x Ag x (SC 8 H 9 ) 60 monolayer-protected clusters (MPCs) using femtosecond time-resolved transient extinction spectroscopy. MPCs provide compositionally well-defined model systems for structure-specific determination of nanoscale electronic properties. Based on pulse-energy-dependent transient extinction data, we quantified electron-phonon coupling constants for three distinct Au 144− x Ag x (SC 8 H 9 ) 60 MPC samples, where x = 0, 0 < x < 30, and x ∼ 30, as G x =0 = (1.61 ± 0.1) × 10 16 W m −3 K −1 , G x