Tip-Enhanced Raman Spectromicroscopy on the Angstrom Scale: Bare and CO-Terminated Ag Tips.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28980800.
- Also identified by DOI 10.1021/acsnano.7b06022.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
The tip is key to the successful execution of tip-enhanced Raman scattering (TERS) measurements in the single molecule limit. We show that nanoscopically smooth silver tips, batch produced through field-directed sputter sharpening, reliably attain TERS with enhancement factors that reach 10<sup>13</sup>, as measured by the Raman spectra of single CO molecules attached to the tip apex. We validate the bare tips by demonstrating spectromicroscopy with submolecular spatial resolution and underscore that TERS is a near-field effect that does not obey simple selection rules. As a more gainful analytical approach, we introduce TERS-relayed molecular force microscopy using CO-terminated tips. By taking advantage of the large Stark tuning rate of the CO stretch, molecular structure and charges can be imaged with atomic resolution. As illustration, we image a single Ag atom adsorbed on Au(111) and show that the adatom carries +0.2e charge.