High-resolution tip-enhanced Raman scattering probes sub-molecular density changes.

ABSTRACT: Tip-enhanced Raman spectroscopy (TERS) exhibits new selection rule and sub-nanometer spatial resolution, which is attributed to the plasmonic near-field confinement. Despite recent advances in simulations of TERS spectra under highly confined fields, a simply physical mechanism has remained elusive. In this work we show that single-molecule TERS images can be explained by local sub-molecular density changes induced by the confined near-field during the Raman process. The local sub-molecular density changes determine the spatial resolution in TERS and the gradient-based selection rule. Using this approach we find that the four-fold symmetry of meso-tetrakis(3,5-di-tert-butylphenyl)porphyrin (H₂TBPP) TERS images observed in experiments arises from the combination of degenerate nor

SUBMITTER: Chen X 

PROVIDER: S-EPMC6561954 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature