Better Resolution of High-Spin Cobalt Hyperfine at Low Frequency: Co-Doped Ba(Zn1/3Ta2/3)O3 as a Model Complex

Abstract

Low-frequency electron paramagnetic resonance (EPR) is used to extract the EPR parameter A-mid and support the approximate X-band value of g-mid for Ba(CoyZn1/3−yTa2/3)O3. Although the cobalt hyperfine structure for the |±1/2〉 state is often unresolved at X-band or S-band, it is resolved in measurements on this compound. This allows for detailed analysis of the molecular orbital for the |±1/2〉 state, which is often the ground state. Moreover, this work shows that the EPR parameters for Co substituted into Zn compounds give important insight into the properties of zinc binding sites.

Recycled and Nickel- or Cobalt-Doped Lead Materials from Lead Acid Battery: Voltammetric and Spectroscopic Studies

“…The line at g ~4.22 is related to the high spin of Co +2 ions (S = 3/2) in octahedral sites while the absorption at g ~2.17 retaliated to the isolated Co +2 ions (S = 3/2), occupying tetrahedral geometries. The resonance signal located at about g ~7.8 were attributed to the S = 3/2 state of the Co +2 ions [ 22 , 23 , 24 ].…”

Resolved Hyperfine at L-band for High-Spin CoEDTA, A Model for Co Sites in Proteins

“…The value in determining an additional parameter, A -mid, is that A -mid is sensitive to the electron density in the | ± 1/2> orbital for the Co complex. The differences in line shape and EPR parameters for Co-doped Ba(Zn 1/3 Ta 2/3 ) O3 , CoBSA, CoCzcP, and Co(D4)(dca) [9,10,11,12] and CoEDTA suggested that low-frequency spectra were sensitive to differences in the electronic configuration. In summary, the best values appeared to be g = 7.8 and A = 84 G for the | ± 3/2> doublet and A -min = 54 G for | ± 1/2> doublet from the X-band spectrum; and g -max = 5.08, g-mid 4.14, A -max = 41 G; A -mid = 38 G from the simulation of the second harmonic L-band spectrum.…”

“…Spectra were recently obtained from a low-frequency spectrometer, as described in [9]. In brief, the L-band and S-band bridges and the loop-gap resonators were homebuilt by the Dr. James S. Hyde laboratory at the National Biomedical EPR Center at the Medical College of Wisconsin (Milwaukee, WI, USA) and are located therein.…”

“…In this study, hyperfine lines for the Co complex of ethylene diamine tetraacetic acid (CoEDTA) are better resolved at L-band, but not at S-band or X-band. The L-band and S-band spectra for a high-spin Co-doped ceramic where the Co hyperfine is resolved at both frequencies was recently published [9]. Although the L-band spectra for several high-spin Co-sites were obtained previously [10,11,12], interpreting the spectra was difficult.…”