scholarly journals EPR Spectroscopy Investigation of Cu2+Ions Adsorbed in Tannin-Formaldehyde Resins of Mimosa (Acacia mearnsii) Bark Extracts

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Marcelo H. Herbst ◽  
Ney V. Vugman
Keyword(s):  
Spectral Resolution ◽  
Epr Spectroscopy ◽  
Chemical Environment ◽  
Broad Line ◽  
Hyperfine Parameters ◽  
Acacia Mearnsii ◽  
Polymeric Network ◽  
Coordination Sites ◽  
Reversible Formation

The chemical environment of Cu2+ions adsorbed in tannin-formaldehyde resins ofAcacia mearnsiibark extracts, prepared from polybutene, is investigated by EPR spectroscopy at 300 K. The spectrum is simulated considering two isolated axial Cu(II) species (Species 1:A∥=16.50(5) mT,A⊥=1.20(10) mT,g∥=2.28(1), andg⊥=2.08(1); Species 2:A∥=15.00(5) mT,A⊥=1.50(10) mT,g∥=2.32(1), andg⊥=2.05(2)), superposed to a broad line (giso=2.14(1); linewidth = 30.0(5) mT) assigned to Cu(II) aggregates. Measurements at 77 K did not improve spectral resolution. Heating at 413 K changes the hyperfine parameters of Species 2 (A∥=14.20(5) mT,A⊥=1.20(10) mT,g∥=2.33(1), andg⊥=2.07(2)) and slightly modifies the parameters of the broad line (giso=2.11(2); linewidth = 40.00(50) mT) but does not change Species 1, assigned to Cu(II) species immobilized into resin pores in cathecolate-type coordination sites. Species 2 is assigned to Cu(II) species immobilized at the outer resin surface. Upon extended heating, a reversible formation of semiquinone-type paramagnetic radicals (giso=2.0037(1)) is observed, assigned to the partial collapse of the resin polymeric network.

scholarly journals Size of the Broad Line Region in NGC 3227: Results from the LAG Campaign

1994 ◽  
Vol 159 ◽  
pp. 457-457
Author(s):  
I. Salamanca ◽  
T. Baribaud ◽  
D. Alloin
Keyword(s):  
Spectral Resolution ◽  
Slit Width ◽  
Broad Line ◽  
Monitoring Campaign ◽  
Broad Line Region ◽  
La Palma ◽  
Line Region

We present the results of a monitoring campaign of the AGN in NGC 3227, conducted at La Palma by the LAG european consortium. The data are long slit spectra, obtained with the 1.5m INT and 4.2m WHT, from January to June 1990. The slit width was 1.5 arcsec. The spectral resolution was about 3 A.

scholarly journals Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

2016 ◽  
Vol 12 ◽  
pp. 2450-2456 ◽  
Author(s):  
Nikolay O Chalkov ◽  
Vladimir K Cherkasov ◽  
Gleb A Abakumov ◽  
Andrey G Starikov ◽  
Viacheslav A Kuropatov
Keyword(s):  
Density Distribution ◽  
Spin Density ◽  
Epr Spectroscopy ◽  
Radical Anion ◽  
Copper Cation ◽  
Chemical Oxidation ◽  
Spin Density Distribution ◽  
Coordination Sites ◽  
Redox Forms ◽  
Anion Species

The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification.

Axial Observation of X-Ray Spectra from a Beam-Foil Source

1988 ◽  
Vol 102 ◽  
pp. 339-342
Author(s):  
J.M. Laming ◽  
J.D. Silver ◽  
R. Barnsley ◽  
J. Dunn ◽  
K.D. Evans ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Heavy Ion ◽  
Ion Beams ◽  
Beam Axis ◽  
Doppler Broadening ◽  
X Ray ◽  
Beam Foil

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.

NMR and EPR Spectroscopy

1963 ◽  
Vol 36 (3_4) ◽  
pp. 247-248
Author(s):  
H. Dreeskamp
Keyword(s):  
Epr Spectroscopy
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