Berlin 2018 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: 2D Materials (Symposium and Joint Session with HL and O): Session I (joint session DS/CPP/HL)

CPP 8.3: Talk

Monday, March 12, 2018, 10:00–10:15, H 2032

Ultra-high vacuum Raman spectroscopy of Cs doped monolayer graphene — •Martin Hell, Boris Senkovskiy, Joshua Hall, Thomas Michely, and Alexander Grüneis — II. Physikalische Institut, Universität zu Köln

We show that ultra-high vacuum (UHV) Raman spectroscopy is a valuable tool for in-situ characterization of epitaxial graphene on Ir(111) regarding strain, defects and doping level. We study the Cs doping induced changes in the Raman spectrum of epitaxial monolayer graphene for 2x2 and √3x√3 Cs adsorption geometries for exciting laser energies in a wide range (325nm to 633nm). The combined effects of lattice expansion and dynamic effects lead to characteristic changes in the Raman spectrum that allow us to identify the charge transfer and the electron-phonon coupling strength from the position, width and asymmetry of the G band Raman line. The electronic and structural characterization of Cs doped graphene is complemented by angle-resolved photoemission measurements and scanning tunneling microscopy on identically prepared samples. The high energy resolution of Raman (∼1 wavenumber) allows for a precise determination of temperature induced strain of epitaxial graphene. Finally, we will show new results regarding the UHV Raman and luminescence characterization of transition metal dichalcogenides grown on graphene/Ir(111).