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TT: Fachverband Tiefe Temperaturen
TT 54: 2D Materials IV: Graphene (joint session O/TT)
TT 54.9: Talk
Wednesday, March 20, 2024, 17:15–17:30, MA 005
Enhancement of graphene phonon excitation by a chemically engineered molecular resonance — Xiaocui Wu1, •Nicolas Néel1, Mads Brandbyge2, and Jörg Kröger1 — 1Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany — 2Center of Nanostructured Graphene, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
The abstraction of pyrrolic hydrogen from a single phthalocyanine on graphene turns the molecule into a sensitive probe for graphene phonons. The inelastic electron transport measured with a scanning tunneling microscope across the molecular adsorbate and graphene becomes strongly enhanced for a graphene out-of-plane acoustic phonon mode. Supporting density functional and transport calculations elucidate the underlying physical mechanism. A molecular orbital resonance close to the Fermi energy controls the inelastic current while specific phonon modes of graphene are magnified due to their coupling to symmetry-equivalent vibrational quanta of the molecule. Funding by the Deutsche Forschungsgemeinschaft through Grant No. KR 2912/17-1 is acknowledged.
Keywords: Scanning tunneling microscope; Inelastic electron tunneling; Phonons; Single molecule chemistry