First-Principles Simulations of Tip Enhanced Raman Scattering Reveal Active Role of Substrate on High-Resolution Images.

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Authors
Akkoush, Alaa 
Appel, Heiko 
Abstract

Tip-enhanced Raman scattering (TERS) has emerged as a powerful tool to obtain subnanometer spatial resolution fingerprints of atomic motion. Theoretical calculations that can simulate the Raman scattering process and provide an unambiguous interpretation of TERS images often rely on crude approximations of the local electric field. In this work, we present a novel and first-principles-based method to compute TERS images by combining Time Dependent Density Functional Theory (TD-DFT) and Density Functional Perturbation Theory (DFPT) to calculate Raman cross sections with realistic local fields. We present TERS results on free-standing benzene and C60 molecules, and on the TCNE molecule adsorbed on Ag(100). We demonstrate that chemical effects on chemisorbed molecules, often ignored in TERS simulations of larger systems, dramatically change the TERS images. This observation calls for the inclusion of chemical effects for predictive theory-experiment comparisons and an understanding of molecular motion at the nanoscale.

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34 Chemical Sciences, 3406 Physical Chemistry
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Sponsorship
H2020 Marie Sklodowska-Curie Actions (895747)
SFB 951 , Deutsche Forschungsgemeinschaft (182087777)
Deutsche Forschungsgemeinschaft (467724959)
Max-Planck-Gesellschaft (NA)