Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 43: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies IV

O 43.7: Talk

Wednesday, March 20, 2024, 12:00–12:15, MA 004

Single-molecule electron-spin resonance by means of atomic force microscopy — Lisanne Sellies, •Sonja Bleher, and Jascha Repp — University of Regensburg, Regensburg, Germany

Recently, we combined electron spin resonance (ESR) and atomic force microscopy (AFM). To this end we drove electron spin transitions between the non-equilibrium triplet states of single molecules, which differ in their lifetimes. Driving these transitions changes the overall triplet lifetime [1], which can be read out with AFM using an electronic pump-probe scheme [2]. The resulting ESR-AFM spectra exhibit a sub-nanoelectronvolt spectral resolution and allow us to distinguish molecules that only differ in their isotopic configuration, as we demonstrated for pentacene [3].

This high spectral resolution allows us to detect minor influences of the local environment. For example, changing the voltage between the tip and the sample, we detected a considerable Stark shift. This Stark shift together with the cantilever oscillation likely contributes substantially to the small but finite linewidth. In this contribution, recent results obtained by ESR-AFM will be presented.

References:

[1] Köhler (1999). Physics Reports, 310, 261-339.

[2] Peng et al. (2021). Science, 373, 452-456.

[3] Sellies et al. (2022). arXiv, arXiv:2212.12244.

Keywords: atomic force microscopy; electron spin resonance; single molecules