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O: Fachverband Oberflächenphysik
O 9: Organic molecules on inorganic substrates: electronic, optical and other properties I
O 9.2: Vortrag
Montag, 9. März 2026, 15:15–15:30, HSZ/0201
Explaining Principles of Tip-Enhanced Raman Images with Ab Initio Modeling — •Krystof Brezina1, Yair Litman2, and Mariana Rossi1 — 1Max-Planck-Institut für Struktur und Dynamik der Materie, Hamburg, Germany — 2Max-Planck-Institut für Polymerforschung, Mainz, Germany
Tip-enhanced Raman spectroscopy (TERS) is an emerging method for imaging vibrational motion and chemically characterizing surface-bound molecular adsorbates. Existing approaches to TERS simulation often build on strong approximations, including a simplification or neglect of the underlying metallic substrate, often leading to discrepancies with experiments. In this work, we present a new, ab initio finite-field formulation of a TERS simulation framework [1] that can efficiently address large-scale, realistic systems under periodic boundary conditions [2]. This treatment is essential as it eliminates known artifacts in simulated TERS images stemming from substrate approximations, as shown by our benchmarks on adsorbates and surface defects, and allows for simulations directly comparable to experiments. In this direction, our simulations of Mg(II)-porphine on Ag(100) correctly explain the spatial intensity variation of experimental TERS images and provide an insight into the fundamental principles that define substrate contribution to the scattering cross section in TERS. Our infrastructure is generally applicable to any solid substrate, is computationally efficient and available within the FHI-aims electronic structure code.
[1] Litman Y. et al. J. Phys. Chem. Lett., 14, 6850–6859 (2023)
[2] Brezina K., Litman Y. and Rossi M. arXiv:2509.13075 (2025)
Keywords: Tip-enhanced Raman spectroscopy; Single-molecule imaging; Substrate-molecule interaction; First-principles calculations; Density-functional theory