Probing the Role of Environmental and Sample Characteristics in Gap Mode Tip-Enhanced Raman Spectroscopy

Tip-enhanced Raman spectroscopy (TERS) has emerged asa powerfulanalytical tool for nondestructive and label-free molecular characterizationat the nanoscale. However, the influence of environmental factorsand sample characteristics on the occurrence of spurious signals,enhancement of TERS signals, and longevity of TERS probes is not wellunderstood yet. Herein, we present a detailed investigation of theinfluence of oxygen, humidity, and atmospheric carbon contaminantson scanning tunneling microscopy-TERS (STM-TERS) measurements of self-assembledmonolayer systems in ambient and inert environments. Our results reveala consistent increase of TERS signals, significant reduction of spurioussignals, and drastically improved longevity of TERS probes in theinert environment. Additionally, sample characteristics such as molecularpacking, chemisorption behavior, and hydrophilicity are found to havea direct impact on signal enhancement in the TERS measurements ofmolecular self-assembled monolayers (SAMs). The novel insights gainedin this study are expected to pave the way for a more robust dataanalysis and improved experimental design in the future gap mode STM-and atomic force microscopy-TERS (AFM-TERS) studies.ISSN:1520-6882ISSN:0003-270