Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 47: Focus Session: Atomic-Scale Studies of Spins on Surfaces with Scanning Tunneling Microscopy 1

O 47.9: Vortrag

Mittwoch, 7. September 2022, 17:30–17:45, S051

Isotope detection inside single molecules in scanning-probe based electron spin resonance — •Lisanne Sellies, Raffael Spachtholz, Philipp Scheuerer, and Jascha Repp — University of Regensburg, Regensburg, Germany

Electron spin resonance (ESR), a versatile technique to study materials with unpaired electrons, was recently combined with scanning tunneling microscopy (STM), bringing atomic-scale spatial resolution to ESR [1]. ESR-STM even allowed detecting strong hyperfine interactions between the single electron spin under study with the atom's nuclear spin [2], due to its largely improved energy resolution compared to conventional STM, reaching the nano-electron-volt regime. This energy resolution could even be improved further if the tunneling current as a read-out was avoided, since this current is the dominating decoherence source for the probed electron spin.

We propose, therefore, a new ESR scanning probe method based on atomic force microscopy (AFM). Since our technique does not rely on the tunneling current to read-out the ESR signal, we increase the coherence times of the electron spins and, consequentially, the energy resolution. Therefore, we can resolve the hyperfine interaction inside organic molecules and distinguish molecules only differing in the isotopic composition. Thus, our technique allows the chemical fingerprinting of molecules and their surroundings.

References: [1] S. Baumann et al., Science 350, 417 (2015) [2] P. Willke et al., Science 362, 336 (2018)