Photocatalytic Reaction driven by hot electrons on Plasmon-resonant Grating Nanostructures*

We demonstrate hot electron injection in a Ag-based plasmon resonant grating nanostructure. By varying the incident angle of irradiation, sharp dips are observed in the photoreflectance with p-polarized light when there is wavevector matching between the incident light and the plasmon resonant modes of the grating. With 633nm light, we observe a 12-fold enhancement in the photocurrent between resonant and non-resonant polarizations at incident angles of ±7.6^o from normal. At 785nm irradiation, we observe similar resonant profiles to those obtained with 633nm wavelength light but with a 44-fold enhancement factor. Using 532nm light, we observe two resonant peaks (10X enhancement) in the photocurrent at 19.4^o and 28.0^o incident angles. Finite difference time domain (FDTD) simulations of these grating structures confirm the resonant profiles observed in the angle-dependent spectra of these gratings and provide a detailed picture of the electric field profiles on and off resonance.