Fermi-edge absorption theory predicting the spectrum A(ω) ∝ ω(-2δ(0)/π+δ(0)92)/π2) relies on the assumption that scattering phase δ(0) is frequency independent. The dependence of δ(0) on ω becomes crucial near the resonant condition, where the phase changes abruptly by π. In this limit, because of the finite time spent by electron on a resonant level, the scattering is dynamic. We incorporate the finite time delay into the theory, solve the Dyson equation with a modified kernel, and find that, near the resonance, A(ω) behaves as ω(-3/4)|lnω|. Scattering off the core hole becomes resonant in 1D and 2D in the presence of an empty subband above the Fermi level; then a deep hole splits off a level from the bottom of this subband. Fermi-edge absorption in the regime when resonant level transforms into a Kondo peak is discussed.
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http://dx.doi.org/10.1103/PhysRevLett.106.197003 | DOI Listing |
Phys Chem Chem Phys
November 2023
Brazilian Center for Research in Physics, Rua Dr Xavier Sigaud 150, Rio de Janeiro, RJ 22290-180, Brazil.
In this study, we have prepared and investigated the electronic properties of a new and promising cobalt doped MnO oxide surface by site-selective and element-sensitive X-ray-absorption (XAS) and photoemission spectroscopy (XPS and resonant PES) combined with density functional theory (DFT) calculations. The crystallinity of both pristine and Co doped thin films was ensured by low energy electron diffraction measurements, in which similar diffraction patterns were obtained for both films suggesting the inclusion of the dopant species within the crystalline MnO thin film. According to our combined experimental data and theoretical calculation results, XAS measurements and replace energy calculations could identify Co impurities adopting preferentially a 2+ oxidation state substituting a Mn cation on tetrahedral sites (80%) as well as the Mn on octahedral sites (20%).
View Article and Find Full Text PDFRSC Adv
April 2023
Institute of High Energy Physics, Chinese Academy of Sciences Beijing 100049 China +86-010-88235992.
Two-dimensional (2D) materials are a very promising material family. The two-dimensional inorganic metal network called BlueP-Au network is rapidly attracting the attention of researchers due to its customizable architecture, adjustable chemical functions and electronic properties. Herein, manganese (Mn) was successfully doped on a BlueP-Au network for the first time, then the doping mechanism and electronic structure evolution was studied by X-ray photoelectron spectroscopy (XPS) based on synchrotron radiation, X-ray absorption spectroscopy (XAS), Scanning Tunneling Microscopy (STM), Density functional theory (DFT), Low-energy electron diffraction (LEED), Angle resolved photoemission spectroscopy (ARPES), Mn atoms tend to be stably adsorbed on two sites of the BlueP-Au network.
View Article and Find Full Text PDFPhys Rev B
February 2022
Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Ag edge x-ray absorption and - Auger electron spectra have been measured and simulated for a variety of x-ray electric-field polarization and Auger electron emission directions. The theory relies on density-functional theory, use of the Bethe-Salpeter equation, atomic multiplet theory, and a simplified model for the Auger line shape and its dependence on photon energy. We also demonstrate that partial densities of states for , , and symmetry partial-wave channels at the Ag site in the solid can be deduced from the experimental measurements with only atomic theoretical input, i.
View Article and Find Full Text PDFJ Chem Phys
November 2015
INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química-Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Buenos Aires C1428EHA, Argentina.
The molecular and electronic structure of Os(II) complexes covalently bonded to self-assembled monolayers (SAMs) on Au(111) surfaces was studied by means of polarization modulation infrared reflection absorption spectroscopy, photoelectron spectroscopies, scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory calculations. Attachment of the Os complex to the SAM proceeds via an amide covalent bond with the SAM alkyl chain 40° tilted with respect to the surface normal and a total thickness of 26 Å. The highest occupied molecular orbital of the Os complex is mainly based on the Os(II) center located 2.
View Article and Find Full Text PDFNano Lett
December 2014
Department of Electrical and Computer Engineering, ‡Department of Materials Science and NanoEngineering, and §Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States.
The gate-controllability of the Fermi-edge onset of interband absorption in graphene can be utilized to modulate near-infrared radiation in the telecommunication band. However, a high modulation efficiency has not been demonstrated to date, because of the small amount of light absorption in graphene. Here, we demonstrate a ∼ 40% amplitude modulation of 1.
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