Picosecond energy transfer at gold/electrolyte interfaces using transient reflecting grating method under surface plasmon resonance condition

The energy transfer dynamics at gold/NaCl aq (0-0.5 M) interfaces was inves tigated using our recently developed surface plasmon resonance transient re flecting grating (SPR-TRG) method. We focused on two exponential decays in the SPR-TRG signals. The two decays correspond to the relaxation of hot ele ctrons and interfacial heat transfer, respectively. The intensity of each d ecay changes systematically with increases in the concentration of NaCl, i. e., the former becomes smaller and the latter becomes larger. Considering t he relation between the intensity and the dynamics, we concluded that there is some interaction between the hot electrons and the adsorbate on the int erface and that the following temperature rise in gold after relaxation of the hot electrons becomes large: This conclusion shows that an ultrafast en ergy transfer processes by hot electrons exists, and that the process is hi ndered by the adsorbate. Finally, we discuss the ultrafast energy transfer in relation to the hot electrons and adsorbate on a molecular scale.