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Abstract

Photon scanning probe microscopy (photon-SPM) provides a promising route to study a lightmatter interaction at the nanometer scale and even down to the single-molecule level, which is an interesting topic not only for fundamental science, but also for a new evolution of nanotechnology. This thesis describes the development of a home-designed low-temperature (LT-) photon-SPM, which combines a parabolic mirror and a lens on the cold STM stage. We demonstrate that this instrument offers a precise beam alignment capability to attain highly reproducible experiments. Using the LT-photon-SPM, we first show a novel plasmon-assisted resonant electron transfer in an scanning tunneling microscope (STM) junction, where resonant electron transfer from a plasmonic tip to field emission resonances (FERs) over a Ag(111) surface is induced by visivble continuous-wave excitation. This process can serve as a simple and intriguing model to examine the interplay between localized surface plasmon excitation and resonant electron transfer in a plasmonic nanocavity. The resonant electron transfer is observed in FER spectroscopy and the plasmon-assisted process is manifested as a downshift of the FER peaks in the spectra. We also examined tip-enhanced Raman spectroscopy (TERS) for ultrathin ZnO layers epitaxially grown on a Ag(111) surface. The local geometric and electronic structure of ZnO/Ag(111) is investigated by combined experiments of STM, STS, and atomic force microscopy. With increasing thickness of the ZnO layers, the conduction band minimum was found to downshift as well as the work function was reduced. Strong TERS signals for 2-ML and 3-ML ZnO were obtained under the conditions where both chemical and physical enhancement mechanisms were satisfied. It is also revealed that the TERS intensity is sensitive to the local electronic structure leading to a high spatial resolution of TERS is below 1 nm.