skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: X-ray natural circular dichroism in copper metaborate

Abstract

The local electronic structure of copper ions in a copper metaborate CuB{sub 2}O{sub 4} crystal is studied on the ESRF synchrotron using X-ray absorption polarization-dependent spectroscopy. The X-ray natural circular dichroism near the K absorption edge of copper is measured in the direction that is perpendicular to crystal axis c. The data obtained indicate the presence of hybridized p–d electronic states of copper. Theoretical calculations are used to separate the contributions of the two crystallographically nonequivalent positions of copper atoms in the unit cell of CuB{sub 2}O{sub 4} to the absorption and X-ray circular dichroism spectra of the crystal.

Authors:
 [1]; ;  [2]; ;  [1];  [3]
  1. Moscow State University (Russian Federation)
  2. European Synchrotron Radiation Facility (France)
  3. Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
Publication Date:
OSTI Identifier:
22617233
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 123; Journal Issue: 1; Other Information: Copyright (c) 2016 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BORATES; COMPUTERIZED SIMULATION; COPPER COMPOUNDS; COPPER IONS; CRYSTALS; DICHROISM; ELECTRONIC STRUCTURE; EUROPEAN SYNCHROTRON RADIATION FACILITY; K ABSORPTION; POLARIZATION; SPECTRA; SPECTROSCOPY; SYNCHROTRON RADIATION; X RADIATION

Citation Formats

Ovchinnikova, E. N., Rogalev, A., Wilhelm, F., Kozlovskaya, K. A., Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru, and Dmitrienko, V. E.. X-ray natural circular dichroism in copper metaborate. United States: N. p., 2016. Web. doi:10.1134/S1063776116050186.
Ovchinnikova, E. N., Rogalev, A., Wilhelm, F., Kozlovskaya, K. A., Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru, & Dmitrienko, V. E.. X-ray natural circular dichroism in copper metaborate. United States. doi:10.1134/S1063776116050186.
Ovchinnikova, E. N., Rogalev, A., Wilhelm, F., Kozlovskaya, K. A., Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru, and Dmitrienko, V. E.. 2016. "X-ray natural circular dichroism in copper metaborate". United States. doi:10.1134/S1063776116050186.
@article{osti_22617233,
title = {X-ray natural circular dichroism in copper metaborate},
author = {Ovchinnikova, E. N. and Rogalev, A. and Wilhelm, F. and Kozlovskaya, K. A. and Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru and Dmitrienko, V. E.},
abstractNote = {The local electronic structure of copper ions in a copper metaborate CuB{sub 2}O{sub 4} crystal is studied on the ESRF synchrotron using X-ray absorption polarization-dependent spectroscopy. The X-ray natural circular dichroism near the K absorption edge of copper is measured in the direction that is perpendicular to crystal axis c. The data obtained indicate the presence of hybridized p–d electronic states of copper. Theoretical calculations are used to separate the contributions of the two crystallographically nonequivalent positions of copper atoms in the unit cell of CuB{sub 2}O{sub 4} to the absorption and X-ray circular dichroism spectra of the crystal.},
doi = {10.1134/S1063776116050186},
journal = {Journal of Experimental and Theoretical Physics},
number = 1,
volume = 123,
place = {United States},
year = 2016,
month = 7
}
  • We report the first measurement of the magnetic circular dichroism (MCD) of the basic polypeptide antibiotic netropsin (Nt). The MCD shows that the longest wavelength absorption band of Nt is the sum of more than one component and permits a radically new interpretation of the circular dichroism of the complex which Nt forms with DNA. We conclude that Nt has no major effect on the CD and thus the helical structure of the bases of the DNA to which it is bound. Thus the ability of Nt to inhibit the function of DNA polymerase, RNA polymerase, and the photoreactivating enzymemore » must be mediated by factors other than a distortion of the helical structure of the bases.« less
  • The electronic and magnetic circular dichroism spectra of thin layers of Cu/sup 1/ and Ag/sup 1/ halides have beem measured at low ( about10 K) temperatures. The med spectra show clear A-terms which, in the case of the silver halides and for one band of cuprous iodide, have unexpected negative signs. A qualitative theoretical interpretation of these signs has been attempted by considering halogen-p and metals/d atomic orbital mixing within the framework of a simple, tight-binding model. Reasonable agreement of theory with experiment has been achieved for the positive copper halide A-terms, but it has not proved possible to obtainmore » by calculation the experimentally observed negative A-term sign of the silver salts and cuprous iodide.« less
  • The circular dichroism (CD) of Pf1 filamentous virus has been examined over the temperature range 0-40/sup 0/C, in the absence and presence of Hg(II), Ag(I), and Cu(II). Thermal difference CD spectra were obtained by subtraction of spectra recorded above and below a thermally induced structure transition near 12/sup 0/C. The thermal difference spectra look like they arise from shifts in two exciton bands, one centered at 230 nm and the other at 290 nm. The amplitudes on either side of a crossover at 230 nm are 10 times those of a crossover at 290 nm. It is proposed that themore » difference spectra result from thermally induced shifts in coupled oscillator interactions between Tyr/sub 40/ residues of the coat protein and the guanine and cytosine bases of the DNA. Metal ions can reduce or block these shifts. The changes in ellipticities at 220, 237, and 270 nm induced by changing the temperature have inflections near 12/sup 0/C. Ag(I) and Hg(II), which are known to bind to the DNA bases in Pf1, reduce or eliminate the inflections in the thermal profiles, depending on the metal ion type and concentration. Cu(II) ions do not affect the profiles. The spectral changes and the effects of the metal ions indicate intimate contact between the DNA bases and the protein subunits in the virion.« less
  • Magnetic circular dichroism (MCD) spectra of several metalloporphyrin complexes of rabbit and human serum hemopexins in the spectral region of 300 to 650 nm and natural circular dichroism (CD) in the 300 to 450 nm region are reported. The MCD spectra of the heme (iron-protoporphyrin IX) complexes of both proteins were essentially identical suggesting similar iron coordination. The Soret region MCD spectrum of ferriheme . hemopexin has a shape and amplitude typical of other completely low spin (S = /sup 1///sub 2/) ferric hemeproteins, and the temperature dependence of the MCD intensity indicates that it is composed predominantly of Faradaymore » C-type, terms. The visible region MCD spectrum of this complex closely resembles those characteristic of cytochrome b/sub 5/ and other bisimidazole-coordinated heme derivatives. Under aerobic conditions, heme . hemopexin is in the fully oxidized state. The ferroheme . hemopexins also exhibit MCD spectra similar to that of ferrocytochrome b/sub 5/, consistent with a low spin state and histidyl side-chain coordination of the heme iorn in the reduced as well as in the oxidized state. The deuteroheme derivatives of rabbit hemopexin exhibit MCD spectra similar to those of the heme complex except for the expected slight differences in wavelength extrema, indicating that the vinyl side chains of protoporphyrin have little influence on the coordination. In contrast, the natural CD spectra of the heme complexes of rabbit and human hemopexin do not resemble the CD of cytochrome b/sub 5/, reflecting differences in the crevice regions of the different hemeproteins. Furthermore, the CD spectra of the ferroheme complexes of rabbit and human hemopexin point to differences in the local environments of the heme chromophores.« less