Theme 3 colloquium: 'Sub-molecular fluorescence microscopy with STM' & 'Atomic-scale spin sensing with a single-molecule at the apex of a scanning tunneling microscope' (Lecture)
- Tuesday 19 November 2019Add to my calendar
- from 16:00
Guillaume Schull and Laurent Limot (Institut de Physique et de Chimie des Matériaux de Strasbourg, France)
Abstract 'Sub-molecular fluorescence microscopy with STM' - Guillaume Schull
The electric current traversing the junction of a scanning tunneling microscope (STM) may lead to a local emission of light that can be used to generate sub-molecularly resolved fluorescence maps of individual molecules. Combined with spectral selection and time-correlated measurements, this hyper-resolved fluorescence microscopy approach allowed us to scrutinize the vibronic structure of individual molecules  in a very similar way than in the recent TERS reports, without requiring an optical excitation. We used this approach to characterize the photonics properties of charged species  and to track the motion of hydrogen atoms within free-based phthalocyanine molecules .
Together with other recent reports [4,5], these results constitute an important step towards photonic measurements with atoms-scale resolution.
fig.: Artistic view of a single ZnPc molecule excited with STM
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 B. Doppagne et al. unpublished
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Abstract 'Atomic-scale spin sensing with a single-molecule at the apex of a scanning tunneling microscope' - Laurent Limot
Recent advances in scanning probe techniques rely on the chemical functionalization of the probe-tip termination with single molecules weakly connected to the metallic apex. Information, otherwise inaccessible with a metallic tip, can be gathered in this way . The success of this approach opens the tantalizing prospect of introducing spin sensitivity through the probe-tip termination by a magnetic molecule. Here, we use a nickelocene-terminated tip (Nc-tip), which offers the possibility of producing spin excitations on the tip apex of a scanning tunneling microscope (STM) [2,3]. We show that when the Nc-tip is a hundred pm away from point contact with a surface-supported object, magnetic effects may be probed through changes in the spin excitation spectrum  of nickelocene. We use this detection scheme to determine the exchange field and the spin polarization of the sample with atomic-scale resolution. Our findings demonstrate that the Nc-tip is a powerful probe for investigating surface magnetism with STM, from single magnetic atoms to surfaces as we exemplify in this talk.
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 M. Ormaza, P. Abufager, B. Verlhac, N. Bachellier, M. L. Bocquet, N. Lorente, L. Limot, Nat. Commun. 8, 1974 (2017).
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