Tip-enhanced Raman spectroscopy (TERS) under ultrahigh vacuum and cryogenic conditions enables exploration of the relations between the adsorption geometry, electronic state, and vibrational fingerprints of individual molecules. TERS capability of reflecting spin states in open-shell molecular configurations is yet unexplored. Here, we use the tip of a scanning probe microscope to lift a perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecule from a metal surface to bring it into an open-shell spin one-half anionic state. We reveal a correlation between the appearance of a Kondo resonance in differential conductance spectroscopy and concurrent characteristic changes captured by the TERS measurements. Through a detailed investigation of various adsorbed and tip-contacted PTCDA scenarios, we infer that the Raman scattering on suspended PTCDA is resonant with a higher excited state. Theoretical simulation of the vibrational spectra enables a precise assignment of the individual TERS peaks to high-symmetry Ag modes, including the fingerprints of the observed spin state. These findings highlight the potential of TERS in capturing complex interactions between charge, spin, and photophysical properties in nanoscale molecular systems and suggest a pathway for designing single-molecule spin-optical devices.

Faculty of Mathematics and Physics Charles University; Ke Karlovu 3 Praha 2 CZ12116 Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences; Flemingovo náměstí 542 2 Praha 6 CZ16000 Czech Republic

Institute of Physics Czech Academy of Sciences; Cukrovarnická 10 112 Praha 6 CZ16200 Czech Republic

Institute of Physics École Polytechnique Fédérale de Lausanne Lausanne CH 1015 Switzerland

Instituto de Ciencia de Materiales de Madrid; CSIC Sor Juana Inés de la Cruz 3 Madrid E28049 Spain

See more in PubMed

Zhang R.; Zhang Y.; Dong Z. C.; Jiang S.; Zhang C.; Chen L. G.; Zhang L.; Liao Y.; Aizpurua J.; Luo Y.; Yang J. L.; Hou J. G. Chemical Mapping of a Single Molecule by Plasmon-Enhanced Raman Scattering. Nature 2013, 498, 82–86. 10.1038/nature12151. PubMed DOI

Lee J.; Crampton K. T.; Tallarida N.; Apkarian V. A. Visualizing Vibrational Normal Modes of a Single Molecule with Atomically Confined Light. Nature 2019, 568, 78–82. 10.1038/s41586-019-1059-9. PubMed DOI

Jaculbia R. B.; Imada H.; Miwa K.; Iwasa T.; Takenaka M.; Yang B.; Kazuma E.; Hayazawa N.; Taketsugu T.; Kim Y. Single-Molecule Resonance Raman Effect in a Plasmonic Nanocavity. Nat. Nanotechnol. 2020, 15, 105–110. 10.1038/s41565-019-0614-8. PubMed DOI

Tallarida N.; Lee J.; Apkarian V. A. Tip-Enhanced Raman Spectromicroscopy on the Angstrom Scale: Bare and CO-Terminated Ag Tips. ACS Nano 2017, 11, 11393–11401. 10.1021/acsnano.7b06022. PubMed DOI

Benz F.; Schmidt M. K.; Dreismann A.; Chikkaraddy R.; Zhang Y.; Demetriadou A.; Carnegie C.; Ohadi H.; De Nijs B.; Esteban R.; Aizpurua J.; Baumberg J. J. Single-Molecule Optomechanics in “Picocavities.. Science 2016, 354, 726–729. 10.1126/science.aah5243. PubMed DOI

Imada H.; Imai-Imada M.; Miwa K.; Yamane H.; Iwasa T.; Tanaka Y.; Toriumi N.; Kimura K.; Yokoshi N.; Muranaka A.; Uchiyama M.; Taketsugu T.; Kato Y. K.; Ishihara H.; Kim Y. Single-Molecule Laser Nanospectroscopy with Micro-Electron Volt Energy Resolution. Science 2021, 373, 95–98. 10.1126/science.abg8790. PubMed DOI

Yang B.; Chen G.; Ghafoor A.; Zhang Y.; Zhang Y.; Zhang Y.; Luo Y.; Yang J.; Sandoghdar V.; Aizpurua J.; Dong Z.; Hou J. G. Sub-Nanometre Resolution in Single-Molecule Photoluminescence Imaging. Nat. Photonics 2020, 14, 693–699. 10.1038/s41566-020-0677-y. DOI

Doležal J.; Sagwal A.; de Campos Ferreira R. C.; Švec M. Single-Molecule Time-Resolved Spectroscopy in a Tunable STM Nanocavity. Nano Lett. 2024, 24, 1629–1634. 10.1021/acs.nanolett.3c04314. PubMed DOI PMC

Doležal J.; Canola S.; Merino P.; Švec M. Exciton-Trion Conversion Dynamics in a Single Molecule. ACS Nano 2021, 15, 7694–7699. 10.1021/acsnano.1c01318. PubMed DOI PMC

Doležal J.; Canola S.; Hapala P.; De Campos Ferreira R. C.; Merino P.; Švec M. Real Space Visualization of Entangled Excitonic States in Charged Molecular Assemblies. ACS Nano 2022, 16, 1082–1088. 10.1021/acsnano.1c08816. PubMed DOI

Doppagne B.; Chong M. C.; Bulou H.; Boeglin A.; Scheurer F.; Schull G. Electrofluorochromism at the Single-Molecule Level. Science 2018, 361, 251–255. 10.1126/science.aat1603. PubMed DOI

Qiu X. H.; Nazin G. V.; Ho W. Vibrationally Resolved Fluorescence Excited with Submolecular Precision. Science 2003, 299, 542–546. 10.1126/science.1078675. PubMed DOI

Sheng S.; Ma R.; Wu J. b.; Li W.; Kong L.; Cong X.; Cao D.; Hu W.; Gou J.; Luo J. W.; Cheng P.; Tan P. H.; Jiang Y.; Chen L.; Wu K. The Pentagonal Nature of Self-Assembled Silicon Chains and Magic Clusters on Ag(110). Nano Lett. 2018, 18, 2937–2942. 10.1021/acs.nanolett.8b00289. PubMed DOI

Zhang Y.; Yang B.; Ghafoor A.; Zhang Y.; Zhang Y. F.; Wang R. P.; Yang J. L.; Luo Y.; Dong Z. C.; Hou J. G. Visually Constructing the Chemical Structure of a Single Molecule by Scanning Raman Picoscopy. Natl. Sci. Rev. 2019, 6, 1169–1175. 10.1093/nsr/nwz180. PubMed DOI PMC

Jiang N.; Foley E. T.; Klingsporn J. M.; Sonntag M. D.; Valley N. A.; Dieringer J. A.; Seideman T.; Schatz G. C.; Hersam M. C.; Van Duyne R. P. Observation of Multiple Vibrational Modes in Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy Combined with Molecular-Resolution Scanning Tunneling Microscopy. Nano Lett. 2012, 12 (10), 5061–5067. 10.1021/nl2039925. PubMed DOI

Mahapatra S.; Ning Y.; Schultz J. F.; Li L.; Zhang J. L.; Jiang N. Angstrom Scale Chemical Analysis of Metal Supported Trans- and Cis-Regioisomers by Ultrahigh Vacuum Tip-Enhanced Raman Mapping. Nano Lett. 2019, 19 (5), 3267–3272. 10.1021/acs.nanolett.9b00826. PubMed DOI

Wang R. P.; Yang B.; Fu Q.; Zhang Y.; Zhu R.; Dong X. R.; Zhang Y.; Wang B.; Yang J. L.; Luo Y.; Dong Z. C.; Hou J. G. Raman Detection of Bond Breaking and Making of a Chemisorbed Up-Standing Single Molecule at Single-Bond Level. J. Phys. Chem. Lett. 2021, 12, 1961–1968. 10.1021/acs.jpclett.1c00074. PubMed DOI

Chiang N.; Chen X.; Goubert G.; Chulhai D. V.; Chen X.; Pozzi E. A.; Jiang N.; Hersam M. C.; Seideman T.; Jensen L.; Van Duyne R. P. Conformational Contrast of Surface-Mediated Molecular Switches Yields Ångstrom-Scale Spatial Resolution in Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy. Nano Lett. 2016, 16, 7774–7778. 10.1021/acs.nanolett.6b03958. PubMed DOI

Xu J.; Zhu X.; Tan S.; Zhang Y.; Li B.; Tian Y.; Shan H.; Cui X.; Zhao A.; Dong Z.; Yang J.; Luo Y.; Wang B.; Hou J. G. Determining Structural and Chemical Heterogeneities of Surface Species at the Single-Bond Limit. Science 2021, 371, 818–822. 10.1126/science.abd1827. PubMed DOI

Ternes M. Probing Magnetic Excitations and Correlations in Single and Coupled Spin Systems with Scanning Tunneling Spectroscopy. Prog. Surf. Sci. 2017, 92, 83–115. 10.1016/j.progsurf.2017.01.001. DOI

Huang Z.; Zhang Y.; He Y.; Song H.; Yin C.; Wu K. A Chemist’s Overview of Surface Electron Spins. Chem. Soc. Rev. 2017, 46, 1955–1976. 10.1039/C6CS00891G. PubMed DOI

Parks J. J.; Champagne A. R.; Costi T. A.; Shum W. W.; Pasupathy A. N.; Neuscamman E.; Flores-Torres S.; Cornaglia P. S.; Aligia A. A.; Balseiro C. A.; Chan G. K. L.; Abruña H. D.; Ralph D. C. Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect. Science 2010, 328, 1370–1373. 10.1126/science.1186874. PubMed DOI

Robles R.; Lorente N.; Isshiki H.; Liu J.; Katoh K.; Breedlove B. K.; Yamashita M.; Komeda T. Spin Doping of Individual Molecules by Using Single-Atom Manipulation. Nano Lett. 2012, 12, 3609–3612. 10.1021/nl301301e. PubMed DOI

Esat T.; Deilmann T.; Lechtenberg B.; Wagner C.; Krüger P.; Temirov R.; Anders F. B.; Rohlfing M.; Tautz F. S. Transfering Spin into an Extended π Orbital of a Large Molecule. Phys. Rev. B - Condens. Matter Mater. Phys. 2015, 91, 14441510.1103/PhysRevB.91.144415. DOI

de la Torre B.; Švec M.; Hapala P.; Redondo J.; Krejčí O.; Lo R.; Manna D.; Sarmah A.; Nachtigallová D.; Tuček J.; Błoński P.; Otyepka M.; Zbořil R.; Hobza P.; Jelínek P. Non-Covalent Control of Spin-State in Metal-Organic Complex by Positioning on N-Doped Graphene. Nat. Commun. 2018, 9, 1–9. 10.1038/s41467-018-05163-y. PubMed DOI PMC

Zhang X.; Wolf C.; Wang Y.; Aubin H.; Bilgeri T.; Willke P.; Heinrich A. J.; Choi T. Electron Spin Resonance of Single Iron Phthalocyanine Molecules and Role of Their Non-Localized Spins in Magnetic Interactions. Nat. Chem. 2022, 14, 59–65. 10.1038/s41557-021-00827-7. PubMed DOI

Cirera B.; Litman Y.; Lin C.; Akkoush A.; Hammud A.; Wolf M.; Rossi M.; Kumagai T. Charge Transfer-Mediated Dramatic Enhancement of Raman Scattering upon Molecular Point Contact Formation. Nano Lett. 2022, 22, 2170–2176. 10.1021/acs.nanolett.1c02626. PubMed DOI PMC

Liu S.; Bonafe F. P.; Appel H.; Rubio A.; Wolf M.; Kumagai T. Inelastic Light Scattering in the Vicinity of a Single-Atom Quantum Point Contact in a Plasmonic Picocavity. ACS Nano 2023, 17, 10172–10180. 10.1021/acsnano.3c00261. PubMed DOI

Yang B.; Chen G.; Ghafoor A.; Zhang Y.; Zhang X.; Li H.; Dong X.; Wang R.; Zhang Y.; Zhang Y.; Dong Z. Chemical Enhancement and Quenching in Single-Molecule Tip-Enhanced Raman Spectroscopy. Angew. Chem. 2023, 135, e20221879910.1002/ange.202218799. PubMed DOI

Cirera B.; Wolf M.; Kumagai T. Joule Heating in Single-Molecule Point Contacts Studied by Tip-Enhanced Raman Spectroscopy. ACS Nano 2022, 16, 16443–16451. 10.1021/acsnano.2c05642. PubMed DOI

Temirov R.; Lassise A.; Anders F. B.; Tautz F. S. Kondo Effect by Controlled Cleavage of a Single-Molecule Contact. Nanotechnology 2008, 19, 06540110.1088/0957-4484/19/6/065401. PubMed DOI

Romaner L.; Nabok D.; Puschnig P.; Zojer E.; Ambrosch-Draxl C. New Journal of Physics Theoretical Study of PTCDA Adsorbed on the Coinage Metal Surfaces, Ag(111), Au(111) and Cu(111). New J. Phys. 2009, 11, 05301010.1088/1367-2630/11/5/053010. DOI

Žonda M.; Stetsovych O.; Korytár R.; Ternes M.; Temirov R.; Raccanelli A.; Tautz F. S.; Jelínek P.; Novotný T.; Švec M. Resolving Ambiguity of the Kondo Temperature Determination in Mechanically Tunable Single-Molecule Kondo Systems. J. Phys. Chem. Lett. 2021, 12, 6320–6325. 10.1021/acs.jpclett.1c01544. PubMed DOI

Esat T.; Friedrich N.; Tautz F. S.; Temirov R. A Standing Molecule as a Single-Electron Field Emitter. Nature 2018, 558, 573–576. 10.1038/s41586-018-0223-y. PubMed DOI

Wagner C.; Green M. F.; Leinen P.; Deilmann T.; Krüger P.; Rohlfing M.; Temirov R.; Tautz F. S. Scanning Quantum Dot Microscopy. Phys. Rev. Lett. 2015, 115, 02610110.1103/PhysRevLett.115.026101. PubMed DOI

Liu S.; Wolf M.; Kumagai T. Plasmon-Assisted Resonant Electron Tunneling in a Scanning Tunneling Microscope Junction. Phys. Rev. Lett. 2018, 121, 22680210.1103/PhysRevLett.121.226802. PubMed DOI

Rohlfing M.; Temirov R.; Tautz F. S. Adsorption Structure and Scanning Tunneling Data of a Prototype Organic-Inorganic Interface: PTCDA on Ag(111). Phys. Rev. B - Condens. Matter Mater. Phys. 2007, 76 (11), 11542110.1103/PhysRevB.76.115421. DOI

Kimura K.; Miwa K.; Imada H.; Imai-Imada M.; Kawahara S.; Takeya J.; Kawai M.; Galperin M.; Kim Y. Selective Triplet Exciton Formation in a Single Molecule. Nature 2019, 570 (7760), 210–213. 10.1038/s41586-019-1284-2. PubMed DOI

Neuman T.; Esteban R.; Casanova D.; García-Vidal F. J.; Aizpurua J. Coupling of Molecular Emitters and Plasmonic Cavities beyond the Point-Dipole Approximation. Nano Lett. 2018, 18, 2358–2364. 10.1021/acs.nanolett.7b05297. PubMed DOI

Neuman T.; Esteban R.; Giedke G.; Schmidt M. K.; Aizpurua J. Quantum Description of Surface-Enhanced Resonant Raman Scattering within a Hybrid-Optomechanical Model. Phys. Rev. A 2019, 100, 04342210.1103/PhysRevA.100.043422. DOI

Scholz R.; Kobitski A. Y.; Kampen T.; Schreiber M.; Zahn D.; Jungnickel G.; Elstner M.; Sternberg M.; Frauenheim T. Resonant Raman Spectroscopy of 3,4,9,10-Perylene-Tetracarboxylic-Dianhydride Epitaxial Films. Phys. Rev. B 2000, 61, 13659.10.1103/PhysRevB.61.13659. DOI

Kobitski A. Y.; Salvan G.; Scholz R.; Tenne D.; Kampen T. U.; Wagner H. P.; Zahn D. R. T. Raman Spectroscopy of the PTCDA–Inorganic Semiconductor Interface: Evidence for Charge Transfer. Appl. Surf. Sci. 2002, 190, 386–389. 10.1016/S0169-4332(01)00898-4. DOI

Frisch M. J.; Trucks G. W.; Schlegel H. B.; Scuseria G. E.; Robb M. A.; Cheeseman J. R.; Scalmani G.; Barone V.; Petersson G. A.; Nakatsuji H.; Li X.; Caricato M.; Marenich A. V.; Bloino J.; Janesko B. G.; Gomperts R.; Mennucci B.; Hratchian H. P.; Ortiz J. V.; Izmaylov A. F.; Sonnenberg J. L.; Williams-Young D.; Ding F.; Lipparini F.; Egidi F.; Goings J.; Peng B.; Petrone A.; Henderson T.; Ranasinghe D.; Zakrzewski V. G.; Gao J.; Rega N.; Zheng G.; Liang W.; Hada M.; Ehara M.; Toyota K.; Fukuda R.; Hasegawa J.; Ishida M.; Nakajima T.; Honda Y.; Kitao O.; Nakai H.; Vreven T.; Throssell K.; Montgomery J. A. J.; Peralta J. E.; Ogliaro F.; Bearpark M. J.; Heyd J. J.; Brothers E. N.; Kudin K. N.; Staroverov V. N.; Keith T. A.; Kobayashi R.; Normand J.; Raghavachari K.; Rendell A. P.; Burant J. C.; Iyengar S. S.; Tomasi J.; Cossi M.; Millam J. M.; Klene M.; Adamo C.; Cammi R.; Ochterski J. W.; Martin R. L.; Morokuma K.; Farkas O.; Foresman J. B.; Fox D. J.. Gaussian 16, Revision A.03; Gaussian, Inc.: Wallingford CT. 2016.

Santoro F.; Lami A.; Improta R.; Bloino J.; Barone V. Effective Method for the Computation of Optical Spectra of Large Molecules at Finite Temperature Including the Duschinsky and Herzberg-Teller Effect: The Qx Band of Porphyrin as a Case Study. J. Chem. Phys. 2008, 128, 29.10.1063/1.2929846. PubMed DOI

Disentangling the components of a multiconfigurational excited state in isolated chromophore with light-scanning-tunneling microscopy

Upgrade of a variable temperature scanning tunneling microscope for nanometer-scale spectromicroscopy