Journal Article

Dual Mode EPR Studies of a Kramers ion: High-Spin Co(II) in 4-, 5- and 6-Coordination

Marts, Amy R., Shim, Sarah W., Oseback, Shannon N., Woodruff, Tessa M., Jacobsen, Faith E., Whitehead, Daniel R., Papish, Elizabeth T., Cohen, Seth M., Greer, Samuel M., Breece, Robert M., Tierney, David L.

2011

Overview

The EPR spectra of high-spin Co(II) systems typically consist of poorly resolved resonances, broadened by a combination of large g -anisotropy, sizable spin–orbit couplings and admixture of excited state character into the magnetic ground state. In this report, we present dual-mode EPR studies of a set of 4-, 5- and 6-coordinate Co(II) complexes, as well as cobalt-substituted carbonic anhydrase, with and without a bidentate chelator. The suite of samples shows surprisingly large signals in parallel mode that cannot be accounted for by imperfections in the isolation of the parallel and perpendicular polarizations. To our knowledge, this is the first report of parallel polarization EPR from a Kramers system. We suggest that the parallel mode signals arise from admixture of excited state character into the ground state, and that the methods employed here may provide a means of quantitatively assessing the extent of mixing.

• Publisher: Springer Vienna,Springer Nature B.V
• Subject: Admixtures / Anisotropy / Atoms and Molecules in Strong Fields / Carbonic anhydrase / Cobalt / Couplings / Excitation / Ground state / Laser Matter Interaction / Organic Chemistry / Physical Chemistry / Physics / Physics and Astronomy / Simulation / Solid State Physics / Spectroscopy/Spectrometry / Spectrum analysis / Temperature