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Sellies L, Spachtholz R, Bleher S, Eckrich J, Scheuerer P, Repp J. Single-molecule electron spin resonance by means of atomic force microscopy. Nature 2023; 624:64-68. [PMID: 38057570 DOI: 10.1038/s41586-023-06754-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/17/2023] [Indexed: 12/08/2023]
Abstract
Understanding and controlling decoherence in open quantum systems is of fundamental interest in science, whereas achieving long coherence times is critical for quantum information processing1. Although great progress was made for individual systems, and electron spin resonance (ESR) of single spins with nanoscale resolution has been demonstrated2-4, the understanding of decoherence in many complex solid-state quantum systems requires ultimately controlling the environment down to atomic scales, as potentially enabled by scanning probe microscopy with its atomic and molecular characterization and manipulation capabilities. Consequently, the recent implementation of ESR in scanning tunnelling microscopy5-8 represents a milestone towards this goal and was quickly followed by the demonstration of coherent oscillations9,10 and access to nuclear spins11 with real-space atomic resolution. Atomic manipulation even fuelled the ambition to realize the first artificial atomic-scale quantum devices12. However, the current-based sensing inherent to this method limits coherence times12,13. Here we demonstrate pump-probe ESR atomic force microscopy (AFM) detection of electron spin transitions between non-equilibrium triplet states of individual pentacene molecules. Spectra of these transitions exhibit sub-nanoelectronvolt spectral resolution, allowing local discrimination of molecules that only differ in their isotopic configuration. Furthermore, the electron spins can be coherently manipulated over tens of microseconds. We anticipate that single-molecule ESR-AFM can be combined with atomic manipulation and characterization and thereby paves the way to learn about the atomistic origins of decoherence in atomically well-defined quantum elements and for fundamental quantum-sensing experiments.
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Affiliation(s)
- Lisanne Sellies
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany.
| | - Raffael Spachtholz
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Sonja Bleher
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Jakob Eckrich
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Philipp Scheuerer
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany.
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2
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Kaiser K, Lieske LA, Repp J, Gross L. Charge-state lifetimes of single molecules on few monolayers of NaCl. Nat Commun 2023; 14:4988. [PMID: 37591847 PMCID: PMC10435478 DOI: 10.1038/s41467-023-40692-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 08/02/2023] [Indexed: 08/19/2023] Open
Abstract
In molecular tunnel junctions, where the molecule is decoupled from the electrodes by few-monolayers-thin insulating layers, resonant charge transport takes place by sequential charge transfer to and from the molecule which implies transient charging of the molecule. The corresponding charge state transitions, which involve tunneling through the insulating decoupling layers, are crucial for understanding electrically driven processes such as electroluminescence or photocurrent generation in such a geometry. Here, we use scanning tunneling microscopy to investigate the decharging of single ZnPc and H2Pc molecules through NaCl films of 3 to 5 monolayers thickness on Cu(111) and Au(111). To this end, we approach the tip to the molecule at resonant tunnel conditions up to a regime where charge transport is limited by tunneling through the NaCl film. The resulting saturation of the tunnel current is a direct measure of the lifetimes of the anionic and cationic states, i.e., the molecule's charge-state lifetime, and thus provides a means to study charge dynamics and, thereby, exciton dynamics. Comparison of anion and cation lifetimes on different substrates reveals the critical role of the level alignment with the insulator's conduction and valence band, and the metal-insulator interface state.
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Affiliation(s)
- Katharina Kaiser
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France.
| | | | - Jascha Repp
- Department of Physics, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Leo Gross
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
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3
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Jiang S, Neuman T, Bretel R, Boeglin A, Scheurer F, Le Moal E, Schull G. Many-Body Description of STM-Induced Fluorescence of Charged Molecules. PHYSICAL REVIEW LETTERS 2023; 130:126202. [PMID: 37027885 DOI: 10.1103/physrevlett.130.126202] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 01/30/2023] [Indexed: 06/19/2023]
Abstract
A scanning tunneling microscope is used to study the fluorescence of a model charged molecule (quinacridone) adsorbed on a sodium chloride (NaCl)-covered metallic sample. Fluorescence from the neutral and positively charged species is reported and imaged using hyperresolved fluorescence microscopy. A many-body model is established based on a detailed analysis of voltage, current, and spatial dependences of the fluorescence and electron transport features. This model reveals that quinacridone adopts a palette of charge states, transient or not, depending on the voltage used and the nature of the underlying substrate. This model has a universal character and clarifies the transport and fluorescence mechanisms of molecules adsorbed on thin insulators.
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Affiliation(s)
- Song Jiang
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Tomáš Neuman
- Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Rémi Bretel
- Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Alex Boeglin
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Fabrice Scheurer
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Eric Le Moal
- Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Guillaume Schull
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
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4
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Friedrich N, Menchón RE, Pozo I, Hieulle J, Vegliante A, Li J, Sánchez-Portal D, Peña D, Garcia-Lekue A, Pascual JI. Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons. ACS NANO 2022; 16:14819-14826. [PMID: 36037149 PMCID: PMC9527809 DOI: 10.1021/acsnano.2c05673] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Spin-hosting graphene nanostructures are promising metal-free systems for elementary quantum spintronic devices. Conventionally, spins are protected from quenching by electronic band gaps, which also hinder electronic access to their quantum state. Here, we present a narrow graphene nanoribbon substitutionally doped with boron heteroatoms that combines a metallic character with the presence of localized spin 1/2 states in its interior. The ribbon was fabricated by on-surface synthesis on a Au(111) substrate. Transport measurements through ribbons suspended between the tip and the sample of a scanning tunneling microscope revealed their ballistic behavior, characteristic of metallic nanowires. Conductance spectra show fingerprints of localized spin states in the form of Kondo resonances and inelastic tunneling excitations. Density functional theory rationalizes the metallic character of the graphene nanoribbon due to the partial depopulation of the valence band induced by the boron atoms. The transferred charge builds localized magnetic moments around the boron atoms. The orthogonal symmetry of the spin-hosting state's and the valence band's wave functions protects them from mixing, maintaining the spin states localized. The combination of ballistic transport and spin localization into a single graphene nanoribbon offers the perspective of electronically addressing and controlling carbon spins in real device architectures.
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Affiliation(s)
| | - Rodrigo E. Menchón
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
| | - Iago Pozo
- CiQUS,
Centro Singular de Investigación en Química Biolóxica
e Materiais Moleculares, 15705 Santiago de Compostela, Spain
| | | | | | - Jingcheng Li
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
| | - Daniel Sánchez-Portal
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Spain
| | - Diego Peña
- CiQUS,
Centro Singular de Investigación en Química Biolóxica
e Materiais Moleculares, 15705 Santiago de Compostela, Spain
| | - Aran Garcia-Lekue
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
| | - José Ignacio Pascual
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
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5
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Peng J, Sokolov S, Hernangómez-Pérez D, Evers F, Gross L, Lupton JM, Repp J. Atomically resolved single-molecule triplet quenching. Science 2021; 373:452-456. [PMID: 34437120 DOI: 10.1126/science.abh1155] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 05/25/2021] [Indexed: 01/14/2023]
Abstract
The nonequilibrium triplet state of molecules plays an important role in photocatalysis, organic photovoltaics, and photodynamic therapy. We report the direct measurement of the triplet lifetime of an individual pentacene molecule on an insulating surface with atomic resolution by introducing an electronic pump-probe method in atomic force microscopy. Strong quenching of the triplet lifetime is observed if oxygen molecules are coadsorbed in close proximity. By means of single-molecule manipulation techniques, different arrangements with oxygen molecules were created and characterized with atomic precision, allowing for the direct correlation of molecular arrangements with the lifetime of the quenched triplet. Such electrical addressing of long-lived triplets of single molecules, combined with atomic-scale manipulation, offers previously unexplored routes to control and study local spin-spin interactions.
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Affiliation(s)
- Jinbo Peng
- Institute for Experimental and Applied Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany.
| | - Sophia Sokolov
- Institute for Experimental and Applied Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Daniel Hernangómez-Pérez
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ferdinand Evers
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
| | - John M Lupton
- Institute for Experimental and Applied Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Jascha Repp
- Institute for Experimental and Applied Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany.
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