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Trainer C, Yim CM, Heil C, Farrar LS, Tsurkan V, Loidl A, Wahl P. Probing Magnetic Exchange Interactions with Helium. Phys Rev Lett 2021; 127:166803. [PMID: 34723611 DOI: 10.1103/physrevlett.127.166803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Controlling and sensing spin polarization of electrons forms the basis of spintronics. Here, we report a study of the effect of helium on the spin polarization of the tunneling current and magnetic contrast in spin-polarized scanning tunneling microscopy (SP STM). We show that the magnetic contrast in SP STM images recorded in the presence of helium depends sensitively on the tunneling conditions. From tunneling spectra and their variation across the atomic lattice we establish that the helium can be reversibly ejected from the tunneling junction by the tunneling electrons. The energy of the tunneling electrons required to eject the helium depends on the relative spin polarization of the tip and sample, making the microscope sensitive to the magnetic exchange interactions. We show that the time-averaged spin polarization of the tunneling current is suppressed in the presence of helium and thereby demonstrate voltage control of the spin polarization of the tunneling current across the tip-sample junction.
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Affiliation(s)
- C Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - C M Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
- Tsung Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - C Heil
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - L S Farrar
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - V Tsurkan
- Center for Electronic Correlations and Magnetism, Experimental Physics V, University of Augsburg, D-86159 Augsburg, Germany
- Institute of Applied Physics, MD 2028 Chisinau, Republic of Moldova
| | - A Loidl
- Center for Electronic Correlations and Magnetism, Experimental Physics V, University of Augsburg, D-86159 Augsburg, Germany
| | - P Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
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Mellor A, Wilson A, Pang CL, Yim CM, Maccherozzi F, Dhesi SS, Muryn CA, Idriss H, Thornton G. Photoemission core level binding energies from multiple sized nanoparticles on the same support: TiO 2(110)/Au. J Chem Phys 2020; 152:024709. [PMID: 31941300 DOI: 10.1063/1.5135760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A novel method of measuring the core level binding energies of multiple sized nanoparticles on the same substrate is demonstrated using the early stage of Au nanoparticle growth on reduced r-TiO2(110). This method employed in situ scanning tunneling microscopy (STM) and microfocused X-ray photoemission spectroscopy. An STM tip-shadowing method was used to synthesize patterned areas of Au nanoparticles on the substrate with different coverages and sizes. Patterns were identified and imaged using a UV photoelectron emission microscope. The Au 4f core level binding energies of the nanoparticles were investigated as a function of Au nanoparticle coverage and size. A combination of initial and final state effects modifies the binding energies of the Au 4f core levels as the nanoparticle size changes. When single Au atoms and Au3 clusters are present, the Au 4f7/2 binding energy, 84.42 eV, is similar to that observed at a high coverage (1.8 monolayer equivalent), resulting from a cancellation of initial and final state effects. As the coverage is increased, there is a decrease in binding energy, which then increases at a higher coverage to 84.39 eV. These results are consistent with a Volmer-Weber nucleation-growth model of Au nanoparticles at oxygen vacancies, resulting in electron transfer to the nanoparticles.
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Affiliation(s)
- Andrew Mellor
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Axel Wilson
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Francesco Maccherozzi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Sarnjeet S Dhesi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Christopher A Muryn
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Hicham Idriss
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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Trainer C, Yim CM, Heil C, Giustino F, Croitori D, Tsurkan V, Loidl A, Rodriguez EE, Stock C, Wahl P. Manipulating surface magnetic order in iron telluride. Sci Adv 2019; 5:eaav3478. [PMID: 30838332 PMCID: PMC6397027 DOI: 10.1126/sciadv.aav3478] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
Control of emergent magnetic orders in correlated electron materials promises new opportunities for applications in spintronics. For their technological exploitation, it is important to understand the role of surfaces and interfaces to other materials and their impact on the emergent magnetic orders. Here, we demonstrate for iron telluride, the nonsuperconducting parent compound of the iron chalcogenide superconductors, determination and manipulation of the surface magnetic structure by low-temperature spin-polarized scanning tunneling microscopy. Iron telluride exhibits a complex structural and magnetic phase diagram as a function of interstitial iron concentration. Several theories have been put forward to explain the different magnetic orders observed in the phase diagram, which ascribe a dominant role either to interactions mediated by itinerant electrons or to local moment interactions. Through the controlled removal of surface excess iron, we can separate the influence of the excess iron from that of the change in the lattice structure.
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Affiliation(s)
- Christopher Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - Chi M. Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
| | - Christoph Heil
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Feliciano Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Dorina Croitori
- Center for Electronic Correlations and Magnetism, Experimental Physics V, University of Augsburg, D-86159 Augsburg, Germany
- Institute of Applied Physics, Academy of Sciences of Moldova, MD 2028 Chisinau, Republic of Moldova
| | - Vladimir Tsurkan
- Center for Electronic Correlations and Magnetism, Experimental Physics V, University of Augsburg, D-86159 Augsburg, Germany
- Institute of Applied Physics, Academy of Sciences of Moldova, MD 2028 Chisinau, Republic of Moldova
| | - Alois Loidl
- Center for Electronic Correlations and Magnetism, Experimental Physics V, University of Augsburg, D-86159 Augsburg, Germany
| | - Efrain E. Rodriguez
- Department of Chemistry of Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Chris Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, UK
| | - Peter Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK
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Yim CM, Chen J, Zhang Y, Shaw BJ, Pang CL, Grinter DC, Bluhm H, Salmeron M, Muryn CA, Michaelides A, Thornton G. Visualization of Water-Induced Surface Segregation of Polarons on Rutile TiO 2(110). J Phys Chem Lett 2018; 9:4865-4871. [PMID: 30081626 DOI: 10.1021/acs.jpclett.8b01904] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Water-oxide surfaces are ubiquitous in nature and of widespread importance to phenomena like corrosion as well as contemporary industrial challenges such as energy production through water splitting. So far, a reasonably robust understanding of the structure of such interfaces under certain conditions has been obtained. Considerably less is known about how overlayer water modifies the inherent reactivity of oxide surfaces. Here we address this issue experimentally for rutile TiO2(110) using scanning tunneling microscopy and photoemission, with complementary density functional theory calculations. Through detailed studies of adsorbed water nanoclusters and continuous water overlayers, we determine that excess electrons in TiO2 are attracted to the top surface layer by water molecules. Measurements on methanol show similar behavior. Our results suggest that adsorbate-induced surface segregation of polarons could be a general phenomenon for technologically relevant oxide materials, with consequences for surface chemistry and the associated catalytic activity.
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Affiliation(s)
- Chi M Yim
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Ji Chen
- Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre , University College London , London WC1E 6BT , United Kingdom
| | - Yu Zhang
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Bobbie-Jean Shaw
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - David C Grinter
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Hendrik Bluhm
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Miquel Salmeron
- Materials Science Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Christopher A Muryn
- School of Chemistry , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Angelos Michaelides
- Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre , University College London , London WC1E 6BT , United Kingdom
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
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Mellor A, Humphrey D, Yim CM, Pang CL, Idriss H, Thornton G. Direct Visualization of Au Atoms Bound to TiO 2(110) O-Vacancies. J Phys Chem C Nanomater Interfaces 2017; 121:24721-24725. [PMID: 29152035 PMCID: PMC5682598 DOI: 10.1021/acs.jpcc.7b09608] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/17/2017] [Indexed: 06/07/2023]
Abstract
Au nanoparticles supported on reducible metal oxide surfaces are known to be active catalysts for a number of reactions including CO oxidation and hydrogen production. The exact choice of a metal oxide support has been shown to have a marked impact on activity, suggesting that interactions between Au and the support play a key role in catalysis. For TiO2, a model substrate for Au catalysis, it had been thought that bridging oxygen vacancies are involved in binding Au atoms to the (110) surface based on indirect evidence. However, a recent scanning transmission electron microscopy study of single Pt atoms on TiO2(110) suggests that subsurface vacancies are more important. To clarify the role of bridging or subsurface vacancies we employ scanning tunneling microscopy to determine the bonding site of single Au atoms on TiO2(110). Using in situ deposition as well as a manipulation method, we provide definitive evidence that the bonding site is atop surface oxygen vacancies.
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Affiliation(s)
- Andrew Mellor
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - David Humphrey
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi M. Yim
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi L. Pang
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Hicham Idriss
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- Fundamental
Catalysis, SABIC-CRI at KAUST, Thuwal, Saudi Arabia
| | - Geoff Thornton
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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Trainer C, Yim CM, McLaren M, Wahl P. Cryogenic STM in 3D vector magnetic fields realized through a rotatable insert. Rev Sci Instrum 2017; 88:093705. [PMID: 28964195 DOI: 10.1063/1.4995688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
Spin-polarized scanning tunneling microscopy (SP-STM) performed in vector magnetic fields promises atomic scale imaging of magnetic structure, providing complete information on the local spin texture of a sample in three dimensions. Here, we have designed and constructed a turntable system for a low temperature STM which in combination with a 2D vector magnet provides magnetic fields of up to 5 T in any direction relative to the tip-sample geometry. This enables STM imaging and spectroscopy to be performed at the same atomic-scale location and field-of-view on the sample, and most importantly, without experiencing any change on the tip apex before and after field switching. Combined with a ferromagnetic tip, this enables us to study the magnetization of complex magnetic orders in all three spatial directions.
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Affiliation(s)
- C Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - C M Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - M McLaren
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - P Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
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Hussain H, Tocci G, Woolcot T, Torrelles X, Pang CL, Humphrey DS, Yim CM, Grinter DC, Cabailh G, Bikondoa O, Lindsay R, Zegenhagen J, Michaelides A, Thornton G. Structure of a model TiO 2 photocatalytic interface. Nat Mater 2017; 16:461-466. [PMID: 27842073 DOI: 10.1038/nmat4793] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/06/2016] [Indexed: 05/21/2023]
Abstract
The interaction of water with TiO2 is crucial to many of its practical applications, including photocatalytic water splitting. Following the first demonstration of this phenomenon 40 years ago there have been numerous studies of the rutile single-crystal TiO2(110) interface with water. This has provided an atomic-level understanding of the water-TiO2 interaction. However, nearly all of the previous studies of water/TiO2 interfaces involve water in the vapour phase. Here, we explore the interfacial structure between liquid water and a rutile TiO2(110) surface pre-characterized at the atomic level. Scanning tunnelling microscopy and surface X-ray diffraction are used to determine the structure, which is comprised of an ordered array of hydroxyl molecules with molecular water in the second layer. Static and dynamic density functional theory calculations suggest that a possible mechanism for formation of the hydroxyl overlayer involves the mixed adsorption of O2 and H2O on a partially defected surface. The quantitative structural properties derived here provide a basis with which to explore the atomistic properties and hence mechanisms involved in TiO2 photocatalysis.
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Affiliation(s)
- H Hussain
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
- ESRF, 6 rue Jules Horowitz, F-38000 Grenoble cedex, France
| | - G Tocci
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - T Woolcot
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - X Torrelles
- Institut de Ciència de Materials de Barcelona (CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - C L Pang
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - D S Humphrey
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - C M Yim
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - D C Grinter
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - G Cabailh
- Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France
| | - O Bikondoa
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry C4 7AL, UK
| | - R Lindsay
- Corrosion and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester M13 9PL, UK
| | - J Zegenhagen
- ESRF, 6 rue Jules Horowitz, F-38000 Grenoble cedex, France
| | - A Michaelides
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
| | - G Thornton
- London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
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Yim CM, Watkins MB, Wolf MJ, Pang CL, Hermansson K, Thornton G. Engineering Polarons at a Metal Oxide Surface. Phys Rev Lett 2016; 117:116402. [PMID: 27661706 DOI: 10.1103/physrevlett.117.116402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 06/06/2023]
Abstract
Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO_{2}(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.
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Affiliation(s)
- C M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - M B Watkins
- School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom
| | - M J Wolf
- Department of Physics & Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - C L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - K Hermansson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - G Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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Abstract
Scanning tunneling microscopy and photoemission spectroscopy have been used to determine the origin of the band-gap state in rutile TiO2(110). This state has long been attributed to oxygen vacancies (O{b} vac). However, recently an alternative origin has been suggested, namely, subsurface interstitial Ti species. Here, we use electron bombardment to vary the O{b} vac density while monitoring the band-gap state with photoemission spectroscopy. Our results show that O{b} vac make the dominant contribution to the photoemission peak and that its magnitude is directly proportional to the O{b} vac density.
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Affiliation(s)
- C M Yim
- London Centre for Nanotechnology and Department of Chemistry, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
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Van Epps HA, Yim CM, Hurley JB, Brockerhoff SE. Investigations of photoreceptor synaptic transmission and light adaptation in the zebrafish visual mutant nrc. Invest Ophthalmol Vis Sci 2001; 42:868-74. [PMID: 11222552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
PURPOSE To characterize the retinal physiology of the zebrafish visual mutant no optokinetic response c (nrc) and to identify the genetic map position of the nrc mutation. METHODS Electroretinograms were recorded from wild-type and nrc zebrafish larvae between 5 to 6 days postfertilization. Responses to flash stimuli, On and Off responses to prolonged light stimuli, and responses to flash stimuli with constant background illumination were characterized. The glutamate agonist, 2-amino-4-phosphonobutyric acid (APB) was used to examine the photoreceptor specific a-wave component of the electroretinogram. Amplified fragment length polymorphism methodology was used to place the nrc mutation on the zebrafish genomic map. RESULTS nrc and wild-type zebrafish larvae 5 to 6 days postfertilization have similar threshold responses to light, but the b-wave of the nrc electroretinogram is significantly delayed and reduced in amplitude. On and Off responses of nrc larvae to prolonged light have multiple oscillations that do not occur in normal zebrafish larvae after 5 days postfertilization. Analysis of the b-wave demonstrated a light adaptation defect in nrc that causes saturation at background light levels approximately 1 order of magnitude less than those with wild-type larvae. Application of the glutamate analog, APB, uncovered the photoreceptor component of the electroretinogram and revealed a light adaptation defect in nrc photoreceptors. The nrc mutation was placed approximately 0.2 cM from sequence length polymorphism marker Z7504 on linkage group 10. CONCLUSIONS The zebrafish mutant nrc is a possible model for human retinal disease. nrc has defects in photoreceptor synaptic transmission and light adaptation. The nrc mutant phenotype shows striking similarities with phenotypes of dystrophin glycoprotein complex mutants, including patients with Duchenne/Becker muscular dystrophy. Localization of the nrc mutation now makes it possible to evaluate candidate genes and clone the nrc gene.
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Affiliation(s)
- H A Van Epps
- Department of Biochemistry, Box 357350, University of Washington, Seattle, WA 98105, USA
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