Nanoraman spectroscopy in low temperature and ultrahigh vacuum environments
Raman spectroscopy is an indispensable tool for materials science research. It has been proven useful for investigating the properties of new materials and discovering their functions. Raman spectroscopy has high chemical sensitivity making it possible to differentiate between two samples having similar structures. Owing to the diffraction limit however, applications of Raman spectroscopy in nanoscale materials is particularly challenging. This, coupled with the inherently weak Raman scattering, has paved way for research trying to solve these fundamental problems. Tip-enhanced Raman spectroscopy (TERS) is one technique that can be used to attain both high spatial resolution and signal enhancement. In TERS, the tip of scanning probe microscope is utilized to direct the incident light to a small area greatly increasing the spatial resolution. Additionally, the tip increases both the excitation and the Raman scattered signal via electromagnetic and chemical enhancement. In this talk, I will present our work on STM-based TERS (STM-TERS) performed at low temperatures and ultrahigh vacuum. These conditions allow for good stability allowing us to investigate single molecules and other nanoscale materials.