Two-photon photoemission spectroscopy for silver nanoparticles on a hydrogen-terminated Si(1 1 1) surface: Metal nanoparticle-enhanced photoemission

Two-photon photoemission (2PPE) spectroscopy was employed for size-selected silver nanoparticles (Ag NPs) deposited on a hydrogen-terminated Si(1 1 1) [H–Si(1 1 1)] to reveal photoemission enhancement through local surface plasmon resonance (LSPR). At low coverage of Ag NPs around 0.005 monolayer equivalents (MLE), the photoemission from the H–Si(1 1 1) substrate was enhanced by ∼2 × 102 times. Above 0.10 MLE, in contrast, photoemission from the Ag NPs themselves was observed. From the experimental results of polarization and the photoemission angle dependence, the photoemission enhancement, depending on the coverage of Ag NPs, is attributed to near-fields from LSPR of Ag NPs.