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Hong SY, Yeh PC, Dadap JI, Osgood RM. Interfacial dipole formation and surface-electron confinement in low-coverage self-assembled thiol layers: thiophenol and p-fluorothiophenol on Cu(111). ACS NANO 2012. [PMID: 23181602 DOI: 10.1021/nn303715d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Model systems of organic self-assembled monolayers are important in achieving full atomic-scale understanding of molecular-electronic interfaces as well as the details of their charge transfer physics. Here we use two-photon photoemission to measure the evolving unoccupied and occupied interfacial electronic structure of two thiolate species, thiophenol and p-fluorothiophenol, adsorbed on Cu(111) as a function of molecular coverage. Our measurements focus on the role of adsorbates in shifting surface polarization and effecting surface electron confinement. As the coverage of each molecule increases, their photoemission-measured work functions exhibit nearly identical behavior up to 0.4-0.5 ML, at which point their behavior diverges; this behavior can be fit to an interfacial bond model for the surface dipole. In addition, our results show the emergence of an interfacial electronic state 0.1-0.2 eV below the Fermi level. This electronic state is attributed to quantum-mechanical-confinement shifting of the Cu(111) surface state by the molecular adsorbates.
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Affiliation(s)
- Sung-Young Hong
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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2
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Heinemann N, Leissner T, Grunau J, Rohwer T, Andreyev O, Bauer M. Two-photon photoemission from ex-situ prepared butanethiol SAMs on Au (111). Chem Phys 2011. [DOI: 10.1016/j.chemphys.2011.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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Lindstrom CD, Zhu XY. Photoinduced Electron Transfer at Molecule−Metal Interfaces. Chem Rev 2006; 106:4281-300. [PMID: 17031987 DOI: 10.1021/cr0501689] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- C D Lindstrom
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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4
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Güdde J, Berthold W, Höfer U. Dynamics of Electronic Transfer Processes at Metal/Insulator Interfaces. Chem Rev 2006; 106:4261-80. [PMID: 17031986 DOI: 10.1021/cr050171s] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J Güdde
- Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, D-35032 Marburg, Germany
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5
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Zhao J, Li B, Onda K, Feng M, Petek H. Solvated Electrons on Metal Oxide Surfaces. Chem Rev 2006; 106:4402-27. [PMID: 17031992 DOI: 10.1021/cr050173c] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jin Zhao
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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6
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Shipman ST, Garrett-Roe S, Szymanski P, Yang A, Strader ML, Harris CB. Determination of Band Curvatures by Angle-Resolved Two-Photon Photoemission in Thin Films of C60 on Ag(111). J Phys Chem B 2006; 110:10002-10. [PMID: 16706459 DOI: 10.1021/jp055042u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The thickness-dependent interfacial band structure was determined for thin films of C(60) on Ag(111) by angle-resolved two-photon photoemission spectroscopy. Dispersions of molecular-orbital derived bands (HOMO, LUMO+1, and LUMO+2) were acquired, and limits were placed on their possible effective masses. A group theoretic approach is also incorporated to further understand the properties of these states. The HOMO, LUMO+1, and LUMO+2 bands possess (best-fit) effective masses of -7 m(e), -7 m(e), and -12 m(e), respectively. These values are consistent with theoretical calculations, averaged over the closely spaced subbands for each state, and provide practical limits on the effective fundamental charge-transport properties of C(60) films.
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Affiliation(s)
- Steven T Shipman
- Chemistry Department, University of California-Berkeley, 94720, USA
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7
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Neuman O, Naaman R. New Optical Absorption Band Resulting from the Organization of Self-Assembled Monolayers of Organic Thiols on Gold. J Phys Chem B 2006; 110:5163-5. [PMID: 16539440 DOI: 10.1021/jp060003j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental evidences are presented supporting the existence of a new optical absorption band observed when monolayers of alkylthiol are self-assembled on gold substrate. This new absorption is centered at about 800 nm and has a very broad absorption peak. The intensity of the new band correlates with the density of molecules and the quality of the organization of the monolayer.
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9
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Lindstrom CD, Muntwiler M, Zhu XY. Electron Transport Across the Alkanethiol Self-assembled Monolayer/Au(111) Interface: Role of the Chemical Anchor. J Phys Chem B 2005; 109:21492-5. [PMID: 16853789 DOI: 10.1021/jp054663k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alkanethiol self-assembled monolayers (SAMs) on Au(111) are model systems for molecular electronics. We probe the role of the chemisorption bond on electron dynamics at the SAM/Au interface using time-resolved two-photon photoemission. Formation of the Au-S bond is evidenced by a localized sigma resonance, which broadens and shifts upward in energy when the lying-down chemisorbed molecules stand up. The localized chemisorption bond does not affect the electronic coupling between delocalized image resonances and the metal substrate. Instead, lifetimes of image resonances are decreased due to scattering with S atoms within the thiol or thiolate monolayer.
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Affiliation(s)
- C D Lindstrom
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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10
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Affiliation(s)
- X.-Y. Zhu
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
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11
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Zangmeister CD, Robey SW, van Zee RD, Yao Y, Tour JM. Valence Electron Orbitals of an Oligo(p-phenylene-ethynylene)thiol on Gold. J Am Chem Soc 2004; 126:3420-1. [PMID: 15025458 DOI: 10.1021/ja0389826] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This communication reports measurement of one-photon (21.2 eV) and one-color, two-photon (3.2-4.5 eV) photoemission spectra of 4,4'-bis-(phenylethynyl)benzenethiol chemisorbed on gold. Four features are observed in these spectra: two occupied, predominantly molecular levels below the Fermi level and two unoccupied, predominantly molecular levels above the Fermi level. The occupied and unoccupied bands closest to the Fermi level are assigned to delocalized pi-bands, and the other occupied and unoccupied bands, to localized pi-bands. With this assignment, the hole- and electron-injection barriers and the transport gap for those levels are deduced.
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12
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Fonticelli M, Azzaroni O, Benítez G, Martins ME, Carro P, Salvarezza RC. Molecular Self-Assembly on Ultrathin Metallic Surfaces: Alkanethiolate Monolayers on Ag(1 × 1)−Au(111). J Phys Chem B 2004. [DOI: 10.1021/jp0359384] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Fonticelli
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
| | - O. Azzaroni
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
| | - G. Benítez
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
| | - M. E. Martins
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
| | - P. Carro
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
| | - R. C. Salvarezza
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La PlataCONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata, Argentina, and Departamento de Química Física, Universidad de La Laguna, Tenerife, Spain
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Bezel I, Gaffney KJ, Garrett-Roe S, Liu SH, Miller AD, Szymanski P, Harris CB. Measurement and dynamics of the spatial distribution of an electron localized at a metal–dielectric interface. J Chem Phys 2004; 120:845-56. [PMID: 15267921 DOI: 10.1063/1.1622386] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ability of time- and angle-resolved two-photon photoemission to estimate the size distribution of electron localization in the plane of a metal-adsorbate interface is discussed. It is shown that the width of angular distribution of the photoelectric current is inversely proportional to the electron localization size within the most common approximations in the description of image potential states. The localization of the n=1 image potential state for two monolayers of butyronitrile on Ag(111) is used as an example. For the delocalized n=1 state, the shape of the signal amplitude as a function of momentum parallel to the surface changes rapidly with time, indicating efficient intraband relaxation on a 100 fs time scale. For the localized state, little change was observed. The latter is related to the constant size distribution of electron localization, which is estimated to be a Gaussian with a 15+/-4 A full width at half maximum in the plane of the interface. A simple model was used to study the effect of a weak localization potential on the overall width of the angular distribution of the photoemitted electrons, which exhibited little sensitivity to the details of the potential. This substantiates the validity of the localization size estimate.
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Affiliation(s)
- Ilya Bezel
- Department of Chemistry, University of California and Chemical Sciences Division, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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14
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Snee PT, Garrett-Roe S, Harris CB. Dynamics of an Excess Electron at Metal/Polar Interfaces. J Phys Chem B 2003. [DOI: 10.1021/jp022665o] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Preston T. Snee
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley, National Laboratory, Berkeley, California 94720
| | - Sean Garrett-Roe
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley, National Laboratory, Berkeley, California 94720
| | - Charles B. Harris
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley, National Laboratory, Berkeley, California 94720
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15
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Mitrasinovic PM. Acrylonitrile (AN)Cu9(100) interfaces: Electron distribution and nature of bonded interactions. CAN J CHEM 2003. [DOI: 10.1139/v03-043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a fundamental interest in the investigation of the interfacial interactions and charge migration processes between organic molecules and metallic surfaces from a theoretical standpoint. Quantum mechanical (QM) concepts of bonding are contrasted, and the vital importance of using combined QM methods to explore the nature of the interfacial interactions is established. At the one-electron level, the charge distribution and nature of bonded interactions at the ANCu9(100) (neutral and charged (1)) interfaces are investigated by both the Becke (B) Vosko (V) Wilk (W) Nusair (N)/DZVP density functional theory (DFT) method and the MP2/631+G* strategy within the conceptual framework provided by natural bond orbital (NBO) natural atomic orbital (NAO) population analysis and Atoms-In-Molecules (AIM) theory. By this approach, the interfacial interactions are given physical definitions free of any assumptions and are visualized by using the topological features of the total electron density. A natural link between the electron density on the one side and the shapes (not energies) of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) on the other side is clarified. The question of whether the spatial extents of the HOMO and LUMO resemble the corresponding spatial maps of the negative (charge locally concentrated) and positive (charge locally depleted) Laplacian of the total electron density in [ANCu9(100)]1 is addressed.Key words: ANCu9(100) interfaces, NBONAO population, electron distribution, AIM, bonded interactions.
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