The effect of STM parameters on tip-enhanced Raman spectra

Faraday Discuss. 2017 Dec 4:205:233-243. doi: 10.1039/c7fd00164a.

Abstract

In this work, we evaluate the dependence of tip-enhanced Raman (TER) spectra of a monolayer of thiophenol at a Au(111) electrode on the scanning tunneling microscope's tunneling current set-point and bias voltage parameters. We find an increase of the TER intensity upon set-point increase or bias decrease as expected from a gap-distance reduction. The relations obtained follow a theoretical model considering a simple gap-distance change when tuning the mentioned parameters. We find that the value of the bias voltage affects the TER intensity to a larger extent than the current set-point. Therefore it is advisable to work in a low-bias regime when aiming for ultrasensitive TER measurements.

Publication types

  • Research Support, Non-U.S. Gov't