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Full-Text Articles in Physics
Unoccupied Orbital Energies Of 1,4-Benzenedithiol And The Homo–Lumo Gap, Adam M. Scheer, Gordon A. Gallup, Paul Burrow
Unoccupied Orbital Energies Of 1,4-Benzenedithiol And The Homo–Lumo Gap, Adam M. Scheer, Gordon A. Gallup, Paul Burrow
Paul Burrow Publications
The energies of the temporary anion states of 1,4-benzenedithiol (BDT) are determined by electron scattering and compared with those computed by density functional theory (DFT) and Hartree–Fock (HF) methods. Using semi-empirical scalings derived from the ionization energies and electron affinities of a series of phenyl–ethynyl compounds, we compute the HOMO–LUMO energy gap of BDT. We show that without such scalings the gap is substantially underestimated using DFT and overestimated using HF methods. Scaled gaps are also determined for several related compounds and compared with experimental measurements in the literature.
Are There Π* Shape Resonances In Electron Scattering From Phosphate Groups?, Paul Burrow, Gordon A. Gallup, Alberto Modelli
Are There Π* Shape Resonances In Electron Scattering From Phosphate Groups?, Paul Burrow, Gordon A. Gallup, Alberto Modelli
Paul Burrow Publications
The temporary anion states of trimethyl phosphate and several compounds bearing the P=O group were explored using electron transmission spectroscopy and ab initio calculations to determine if these states have the characteristics of the π* resonances usually associated with multiple bonds. No evidence was found for this in (CH3O)3PO and, by extension, we do not expect them to appear in the phosphate group of DNA. Cl3PO, however, does display such characteristics to some extent, and we show that they arise from the spatial properties of the π* (P-Cl) orbitals rather than from multiple PO …
Charge Order, Dynamics, And Magnetostructural Transition In Multiferroic Lufe2o4, X. S. Xu, M. Angst, T. V. Brinzari, R. P. Hermann, J. L. Musfeldt, A. D. Christianson, D. Mandrus, B. C. Sales, S. Mcgill, J. -W. Kim, Z. Islam
Charge Order, Dynamics, And Magnetostructural Transition In Multiferroic Lufe2o4, X. S. Xu, M. Angst, T. V. Brinzari, R. P. Hermann, J. L. Musfeldt, A. D. Christianson, D. Mandrus, B. C. Sales, S. Mcgill, J. -W. Kim, Z. Islam
Xiaoshan Xu Papers
We investigated the series of temperature and field-driven transitions in LuFe2O4 by optical and Mossbauer spectroscopies, magnetization, and x-ray scattering in order to understand the interplay between charge, structure, and magnetism in this multiferroic material. We demonstrate that charge fluctuation has an onset well below the charge ordering transition, supporting the ‘‘order by fluctuation’’ mechanism for the development of charge order superstructure. Bragg splitting and large magneto-optical contrast suggest a low-temperature monoclinic distortion that can be driven by both temperature and magnetic field.
Photoconductivity In Bifeo3 Thin Films, S. R. Basu, L. W. Martin, Y. H. Chu, M. Gajek, R. Ramesh, R. C. Rai, X. S. Xu, J. L. Musfeldt
Photoconductivity In Bifeo3 Thin Films, S. R. Basu, L. W. Martin, Y. H. Chu, M. Gajek, R. Ramesh, R. C. Rai, X. S. Xu, J. L. Musfeldt
Xiaoshan Xu Papers
The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17 eV, a direct gap (2.667±0.005 eV at 300 K), and charge transfer excitations at higher energy. Additionally, we report photoconductivity in BiFeO3 films under illumination from a 100 mW/cm2 white light source. A direct correlation is observed between the magnitude of the photoconductivity and postgrowth cooling pressure. Dark conductivities increased by an order of magnitude when comparing films cooled in 760 and 0.1 Torr. Large increases in photoconductivity are observed in light.
Optical Band Gap Of Bifeo3 Grown By Molecular-Beam Epitaxy, J. F. Ihlefeld, N. J. Podraza, Z. K. Liu, R. C. Rai, X. Xu, T. Heeg, Y. B. Chen, J. Li, R. W. Collins, J. L. Musfeldt, X. Q. Pan, J. Schubert, R. Ramesh, D. G. Schlom
Optical Band Gap Of Bifeo3 Grown By Molecular-Beam Epitaxy, J. F. Ihlefeld, N. J. Podraza, Z. K. Liu, R. C. Rai, X. Xu, T. Heeg, Y. B. Chen, J. Li, R. W. Collins, J. L. Musfeldt, X. Q. Pan, J. Schubert, R. Ramesh, D. G. Schlom
Xiaoshan Xu Papers
BiFeO3 thin films have been deposited on (001) SrTiO3 substrates by adsorption-controlled reactive molecular-beam epitaxy. For a given bismuth overpressure and oxygen activity, single-phase BiFeO3 films can be grown over a range of deposition temperatures in accordance with thermodynamic calculations. Four-circle x-ray diffraction reveals phase-pure, epitaxial films with w rocking curve full width at half maximum values as narrow as 29 arc sec (0.008°). Multiple-angle spectroscopic ellipsometry reveals a direct optical band gap at 2.74 eV for stoichiometric as well as 5% bismuth-deficient single-phase BiFeO3 films.