76
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Pascual JI, Barth JV, Ceballos G, Trimarchi G, De Vita A, Kern K, Rust HP. Mesoscopic chiral reshaping of the Ag(110) surface induced by the organic molecule PVBA. J Chem Phys 2004; 120:11367-70. [PMID: 15268168 DOI: 10.1063/1.1763836] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report scanning tunneling microscopy observations on the restructuring of a Ag(110) surface induced by the molecule 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA). Our data reveal that the surface undergoes a mesoscopic step faceting following exposure to submonolayer coverages and thermal activation. A sawtooth arrangement evolves implying long-range mass transport of substrate atoms and forming a regular arrangement of kink sites. Its formation is associated with the molecules' functional headgroups forming carboxylates with [100] Ag microfacets at step edges, and eventually operating to reshape the surface morphology. Interestingly, the resulting microfacets act as chiral templates for the growth of supramolecular PVBA structures. Theoretical modeling based on ab initio results indicates that chiral recognition processes discriminating between the two enantiomers of adsorbed PVBA molecules occur in this process.
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77
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Rastelli A, Stufler S, Schliwa A, Songmuang R, Manzano C, Costantini G, Kern K, Zrenner A, Bimberg D, Schmidt OG. Hierarchical self-assembly of GaAs/AlGaAs quantum dots. PHYSICAL REVIEW LETTERS 2004; 92:166104. [PMID: 15169246 DOI: 10.1103/physrevlett.92.166104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2003] [Indexed: 05/24/2023]
Abstract
A novel structure containing self-assembled, unstrained GaAs quantum dots is obtained by combining solid-source molecular beam epitaxy and atomic-layer precise in situ etching. Photo-luminescence (PL) spectroscopy reveals light emission with very narrow inhomogeneous broadening and clearly resolved excited states at high excitation intensity. The dot morphology is determined by scanning probe microscopy and, combined with single band and eight-band k.p theory calculations, is used to interpret PL and single-dot spectra with no adjustable structural parameter.
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78
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Knez M, Sumser MP, Bittner AM, Wege C, Jeske H, Hoffmann DMP, Kuhnke K, Kern K. Binding the tobacco mosaic virus to inorganic surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:441-447. [PMID: 15743089 DOI: 10.1021/la035425o] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We studied the adsorption behavior and surface chemistry of the tobacco mosaic virus (TMV) on well-defined metal and insulator surfaces. TMV serves as a tubular supramolecular model system with precisely known surface termination. We show that if the surface chemistry of the substrate and the pH-dependent chemistry of the molecular surface match, for example, by hydrogen bonding, a strong adsorption occurs, and lateral movement is impeded. Due to the immobilization, the virion can be imaged by atomic force microscopy (AFM) in contact mode. We also used self-assembled monolayers with an acyl chloride group to induce covalent bonding via ester formation. Noncontact AFM proved that TMV keeps its cylindrical cross section only under weak adsorption conditions, that is, on hydrophobic surfaces, while on hydrophilic substrates a deformation occurs to maximize the number of interacting chemical groups.
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79
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Wahl P, Schneider MA, Diekhöner L, Vogelgesang R, Kern K. Quantum coherence of image-potential states. PHYSICAL REVIEW LETTERS 2003; 91:106802. [PMID: 14525497 DOI: 10.1103/physrevlett.91.106802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2003] [Indexed: 05/24/2023]
Abstract
The quantum dynamics of the two-dimensional image-potential states in front of the Cu(100) surface is measured by scanning tunneling microscopy and spectroscopy. The dispersion relation and the momentum resolved phase-relaxation time of the first image-potential state are determined from the quantum interference patterns in the local density of states at step edges. It is demonstrated that the tip-induced Stark shift does not affect the motion of the electrons parallel to the surface.
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80
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Diekhöner L, Schneider MA, Baranov AN, Stepanyuk VS, Bruno P, Kern K. Surface states of cobalt nanoislands on Cu111. PHYSICAL REVIEW LETTERS 2003; 90:236801. [PMID: 12857277 DOI: 10.1103/physrevlett.90.236801] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Indexed: 05/24/2023]
Abstract
The electronic structure of thin Co nanoislands on Cu(111) has been investigated below and above the Fermi level (E(F)) by scanning tunneling spectroscopy at low temperature. Two surface related electronic states are found: a strong localized peak 0.31 eV below E(F) and a mainly unoccupied dispersive state, giving rise to quantum interference patterns of standing electron waves on the Co surface. Ab initio calculations reveal that the electronic states are spin polarized, originating from d3(z(2)-r(2))-minority and sp-majority bands, respectively.
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81
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Enders A, Peterka D, Repetto D, Lin N, Dmitriev A, Kern K. Temperature dependence of the surface anisotropy of Fe ultrathin films on Cu(001). PHYSICAL REVIEW LETTERS 2003; 90:217203. [PMID: 12786584 DOI: 10.1103/physrevlett.90.217203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Indexed: 05/24/2023]
Abstract
We report an experimental approach to separate temperature dependent reversible and irreversible contributions to the perpendicular magnetic anisotropy of Fe films grown at low temperatures on Cu(001) substrates. The surface anisotropy K(S)(T) is found to decrease linearly with temperature, causing a thermally induced spin reorientation into the plane. The irreversible shift of the spin reorientation transition and the coercivity of the iron films are directly correlated to the increasing Fe island size during annealing. The increased coercivity is discussed in terms of domain wall energy inhomogeneities provided by the islands.
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82
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Gambardella P, Rusponi S, Veronese M, Dhesi SS, Grazioli C, Dallmeyer A, Cabria I, Zeller R, Dederichs PH, Kern K, Carbone C, Brune H. Giant magnetic anisotropy of single cobalt atoms and nanoparticles. Science 2003; 300:1130-3. [PMID: 12750516 DOI: 10.1126/science.1082857] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic anisotropy energy is further shown to be dependent on single-atom coordination changes. These results confirm theoretical predictions and are of fundamental value to understanding how magnetic anisotropy develops in finite-sized magnetic particles.
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83
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Krstić V, Roth S, Burghard M, Kern K, Rikken GLJA. Magneto-chiral anisotropy in charge transport through single-walled carbon nanotubes. J Chem Phys 2002. [DOI: 10.1063/1.1523895] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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84
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Bürgi L, Brune H, Kern K. Imaging of electron potential landscapes on Au(111). PHYSICAL REVIEW LETTERS 2002; 89:176801. [PMID: 12398693 DOI: 10.1103/physrevlett.89.176801] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2002] [Indexed: 05/24/2023]
Abstract
The Hohenberg-Kohn theorem states that the ground state electron density completely determines the external potential acting on an electron system. Inspired by this fundamental theorem, we developed a novel approach to map directly the electron potential in surface systems: linear response theory applied to the total electron density as measured with scanning tunneling microscopy determines the external potential. Potential imaging is demonstrated for the s-p derived surface state on Au(111), where the "herringbone" reconstruction induces a periodic potential modulation, the details of which are revealed by our technique.
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85
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Dmitriev A, Lin N, Weckesser J, Barth JV, Kern K. Supramolecular Assemblies of Trimesic Acid on a Cu(100) Surface. J Phys Chem B 2002. [DOI: 10.1021/jp014214u] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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86
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Gambardella P, Dallmeyer A, Maiti K, Malagoli MC, Eberhardt W, Kern K, Carbone C. Ferromagnetism in one-dimensional monatomic metal chains. Nature 2002; 416:301-4. [PMID: 11907571 DOI: 10.1038/416301a] [Citation(s) in RCA: 744] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two-dimensional systems, such as ultrathin epitaxial films and superlattices, display magnetic properties distinct from bulk materials. A challenging aim of current research in magnetism is to explore structures of still lower dimensionality. As the dimensionality of a physical system is reduced, magnetic ordering tends to decrease as fluctuations become relatively more important. Spin lattice models predict that an infinite one-dimensional linear chain with short-range magnetic interactions spontaneously breaks up into segments with different orientation of the magnetization, thereby prohibiting long-range ferromagnetic order at a finite temperature. These models, however, do not take into account kinetic barriers to reaching equilibrium or interactions with the substrates that support the one-dimensional nanostructures. Here we demonstrate the existence of both short- and long-range ferromagnetic order for one-dimensional monatomic chains of Co constructed on a Pt substrate. We find evidence that the monatomic chains consist of thermally fluctuating segments of ferromagnetically coupled atoms which, below a threshold temperature, evolve into a ferromagnetic long-range-ordered state owing to the presence of anisotropy barriers. The Co chains are characterized by large localized orbital moments and correspondingly large magnetic anisotropy energies compared to two-dimensional films and bulk Co.
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87
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Weckesser J, Cepek C, Fasel R, Barth JV, Baumberger F, Greber T, Kern K. Binding and ordering of C60 on Pd(110): Investigations at the local and mesoscopic scale. J Chem Phys 2001. [DOI: 10.1063/1.1410391] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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88
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89
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Weckesser J, De Vita A, Barth JV, Cai C, Kern K. Mesoscopic correlation of supramolecular chirality in one-dimensional hydrogen-bonded assemblies. PHYSICAL REVIEW LETTERS 2001; 87:096101. [PMID: 11531578 DOI: 10.1103/physrevlett.87.096101] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2000] [Indexed: 05/23/2023]
Abstract
The ordering of 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid, a two-dimensional chiral species, was studied by scanning tunneling microscopy at noble metal surfaces. Homochiral molecules self-assemble in supramolecular chiral hydrogen-bonded twin chains, which order in nanogratings where the supramolecular chirality is strictly correlated over the entire microm domains without intimate molecular contact. Model simulations indicate that the underlying mesoscopic chiral resolution is associated with twin chains acting as chiroselective templates for transient molecular attachment, which process mediates the gratings' evolution.
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90
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Gambardella P, Sljivancanin Z, Hammer B, Blanc M, Kuhnke K, Kern K. Oxygen dissociation at Pt steps. PHYSICAL REVIEW LETTERS 2001; 87:056103. [PMID: 11497791 DOI: 10.1103/physrevlett.87.056103] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2000] [Revised: 01/22/2001] [Indexed: 05/23/2023]
Abstract
Using scanning tunneling microscopy, thermal energy atom scattering, and density functional theory we have characterized O (2) dissociation on Pt(111) stepped surfaces at the atomic scale. The most reactive site is at the top of the Pt steps. In both the molecular precursor state (MPS) and the transition state (TS), the O (2) has its axis aligned parallel to the step edge. Controlled step decoration with Ag monatomic chains was used to locally tune the reactivity of Pt step sites. The enhanced reactivity at the Pt step sites is not caused by a decrease of the local dissociation barriers from the MPS but is related to a stabilization of both the MPS and TS.
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91
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Weil MH, Becker L, Budinger T, Kern K, Nichol G, Shechter I, Traystman R, Wiedemann H, Wise R, Weisfeldt M, Sopko G. Post resuscitative and initial utility in life saving efforts (pulse): a workshop executive summary. Resuscitation 2001; 50:23-5. [PMID: 11724009 DOI: 10.1016/s0300-9572(01)00386-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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92
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Harry Weil M, Becker L, Budinger T, Kern K, Nichol G, Shechter I, Traystman R, Wiedemann H, Weisfeldt M, Sopko G. Workshop executive summary report: Postresuscitative and initial utility in life-saving efforts (PULSE), June 29–30, 2000, Lansdowne Resort and Conference Center, Leesburg, VA. Crit Care Med 2001; 29:878-9. [PMID: 11373486 DOI: 10.1097/00003246-200104000-00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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93
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Weil MH, Becker L, Budinger T, Kern K, Nichol G, Shechter I, Traystman R, Wiedemann H, Wise R, Weisfeldt M, Sopko G. Workshop Executive Summary Report: Post-resuscitative and initial Utility in Life Saving Efforts (PULSE): June 29-30, 2000; Lansdowne Resort and Conference Center; Leesburg, VA. Circulation 2001; 103:1182-4. [PMID: 11238256 DOI: 10.1161/01.cir.103.9.1182] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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94
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Barth JV, Weckesser J, Cai C, Günter P, Bürgi L, Jeandupeux O, Kern K. Building Supramolecular Nanostructures at Surfaces by Hydrogen Bonding Fruitful discussions with A. de Vita, B. Müller, and H. Brune are acknowleged. Angew Chem Int Ed Engl 2000; 39:1230-1234. [PMID: 10767015 DOI: 10.1002/(sici)1521-3773(20000403)39:7<1230::aid-anie1230>3.0.co;2-i] [Citation(s) in RCA: 225] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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95
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Kern K, Langevin PB, Dunn BM. Methemoglobinemia after topical anesthesia with lidocaine and benzocaine for a difficult intubation. J Clin Anesth 2000; 12:167-72. [PMID: 10818334 DOI: 10.1016/s0952-8180(00)00113-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Methemoglobinemia is an uncommon cause of cyanosis; however, rapid diagnosis is critical to avoid potentially fatal consequences. Several local anesthetics can precipitate methemoglobinemia in susceptible patients. This case report of acute methemoglobinemia occurred during fiberoptic intubation in an awake patient without a past medical history of adverse reactions to local anesthetics.
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96
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Barth JV, Brune H, Fischer B, Weckesser J, Kern K. Dynamics of surface migration in the weak corrugation regime. PHYSICAL REVIEW LETTERS 2000; 84:1732-1735. [PMID: 11017612 DOI: 10.1103/physrevlett.84.1732] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/1999] [Indexed: 05/23/2023]
Abstract
We report a systematic study for metal-on-metal surface migration in the weak corrugation regime, i.e., with migration barriers falling below approximately 100 meV. The migration characteristics are elucidated by variable-temperature scanning tunneling microscopy observations in the 50-200 K temperature range, which are analyzed by means of nucleation theory. The results demonstrate that, upon entering the weak corrugation regime, the dynamics of the systems are characterized by increasingly reduced effective preexponential factors, while Arrhenius behavior prevails.
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97
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Cavalleri O, Bittner AM, Kind H, Kern K, Greber T. Copper Electrodeposition on Alkanethiolate Covered Gold Electrodes*. ACTA ACUST UNITED AC 1999. [DOI: 10.1524/zpch.1999.208.part_1_2.107] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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98
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Cummins RO, Hazinski MF, Kerber RE, Kudenchuk P, Becker L, Nichol G, Malanga B, Aufderheide TP, Stapleton EM, Kern K, Ornato JP, Sanders A, Valenzuela T, Eisenberg M. Low-energy biphasic waveform defibrillation: evidence-based review applied to emergency cardiovascular care guidelines: a statement for healthcare professionals from the American Heart Association Committee on Emergency Cardiovascular Care and the Subcommittees on Basic Life Support, Advanced Cardiac Life Support, and Pediatric Resuscitation. Circulation 1998; 97:1654-67. [PMID: 9593576 DOI: 10.1161/01.cir.97.16.1654] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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99
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Schuster R, Robinson IK, Kuhnke K, Ferrer S, Alvarez J, Kern K. Pokrovsky-Talapov commensurate-incommensurate transition in the CO/Pd(100) system. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:17097-17101. [PMID: 9985843 DOI: 10.1103/physrevb.54.17097] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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100
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Müller B, Nedelmann L, Fischer B, Brune H, Kern K. Initial stages of Cu epitaxy on Ni(100): Postnucleation and a well-defined transition in critical island size. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:17858-17865. [PMID: 9985917 DOI: 10.1103/physrevb.54.17858] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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