Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 91: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales III
O 91.3: Talk
Thursday, March 21, 2024, 15:45–16:00, MA 041
Tip-enhanced Raman spectroscopy of physisorbed molecular hydrogen — •Akitoshi Shiotari1, Shuyi Liu2, Heiko Appel3, Adnan Hammud1, Toshiki Sugimoto4, Jun Yoshinobu5, Martin Wolf1, Mariana Rossi3, and Takashi Kumagai4 — 1Fritz-Haber Institute of the Max-Planck Society, Berlin, Germany — 2Huazhong University of Science and Technology, Wuhan, China — 3Max-Planck-Institute for Structure and Dynamics of Matter, Hamburg, Germany — 4Institute for Molecular Science, Okazaki, Japan — 5Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
Hydrogen molecules on metals is an important model system for understanding physisorption. However, characterizing such weakly adsorbed molecules has been technically challenging. We demonstrate that tip-enhanced Raman spectroscopy (TERS), when combined with scanning tunneling microscopy (STM) at cryogenic temperatures, is capable of detecting physisorbed adsorbates. The rotational and vibrational modes of hydrogen molecules on a Ag(111) surface are characterized using TERS, revealing the nature of the nearly-free rotor. Additionally, we find that the electromagnetic mechanism predominantly contributes to the enhancement of Raman scattering, thus enabling sensitive detection and providing local information on the physisorption system.
Keywords: TERS; scanning probe microscopy; H2; physisorption; plasmonic field