title: Intramolecular insight into adsorbate-substrate interactions via low-temperature, ultrahigh-vacuum tip-enhanced Raman spectroscopy.
abstract: Tip-enhanced Raman spectroscopy (TERS) provides chemical information for adsorbates with nanoscale spatial resolution, single-molecule sensitivity, and, when combined with scanning tunneling microscopy (STM), Ångstrom-scale topographic resolution. Performing TERS under ultrahigh-vacuum conditions allows pristine and atomically smooth surfaces to be maintained, while liquid He cooling minimizes surface diffusion of adsorbates across the solid surface, allowing direct STM imaging. Low-temperature TER (LT-TER) spectra differ from room-temperature TER (RT-TER), RT surface-enhanced Raman (SER), and LT-SER spectra because the vibrational lines are narrowed and shifted, revealing additional chemical information about adsorbate-substrate interactions. As an example, we present LT-TER spectra for the rhodamine 6G (R6G)/Ag(111) system that exhibit such unique spectral shifts. The high spectral resolution of LT-TERS provides intramolecular insight in that the shifted modes are associated with the ethylamine moiety of R6G. LT-TERS is a promising approach for unraveling the intricacies of adsorbate-substrate interactions that are inaccessible by other means.
authors.affiliation: Northwestern University , Department of Chemistry, 2145 Sheridan Road, Evanston, IL 60208, United States.
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Klingsporn
authors.forename: Nan
authors.initials: N
authors.lastname: Jiang
authors.forename: Eric A
authors.initials: EA
authors.lastname: Pozzi
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Sonntag
authors.forename: Dhabih
authors.initials: D
authors.lastname: Chulhai
authors.forename: Tamar
authors.initials: T
authors.lastname: Seideman
authors.forename: Lasse
authors.initials: L
authors.lastname: Jensen
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
authors.forename: Richard P
authors.initials: RP
authors.lastname: Van Duyne
mesh_terms: D000327:Adsorption; D003080:Cold Temperature; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D012235:Rhodamines; C026188:rhodamine 6G; D012834:Silver