Multi frequency EPR

Analysis of the spectra at different frequencies yielded the parameters D = — 2.20(5) cm-1, = 0.0(1) cm-1, and a nearly isotropic g-factor, g = 1.98(2), none of which could have been determined at X-band. Analysis was aided by the observation of different slopes of the B vs. v plots for Ams > 1 and Ams = 1 transitions. A review of advanced methods, including high-field EPR, is given in ref. 11. Various recent applications of high field and multi-frequency EPR are described in refs 19-31. 

P.J.M. van Kan, E. van der Horst, E.J. Reijerse, P.J.M. van Bentum and W.R. Hagen, Multi-frequency EPR spectroscopy of myoglobin. Spectral effects for high-spin iron(III) at high magnetic fields, J. Chem. Soc., Faraday Trans., 1998, 94, 2975. 

Pierik, A.J., Hagen, W.R., Dunham, W.R., and Sands, R.H. 1992a. Multi-frequency EPR and high-resolution Mossbauer spectroscopy of a putative [6Fe-6S] prismane-cluster-containing protein from Desulfovibrio vulgaris (Hildenborough) characterization of a supercluster and superspin model protein. European Journal of Biochemistry 206 705-719. 

Multi-frequency EPR and High-Frequency EPR Tie, T2e (ts) geffective. Through analysis of the field/frequency dependence of electronic relaxation and geffective zero field splitting (ZFS, D, E, A2), rv. Also details of BPCA-protein interactions, including BPCA fraction bound to protein. 

The main advantage of a multi-frequency study is that it provides information on the frequency dispersion of magnetic resonance parameters. This approach (dispersion), for example, is the power in NMRD studies. Several laboratories pioneered in the application of multi-frequency EPR as a route to a more accurate evaluation of key spectroscopic parameters (g, A, Q, D, E), as well as a more sensitive methodology for studying dynamical processes, where an interplay between the frequency dependence of the spin process and the frequency dependence of the EPR observation often can provide exceptionally detailed information [64,65]. In order to take advantage of the method, the frequency dependence of spin systems must be understood. This has led to the development of several theoretical approaches for better analysis of multi-frequency data, and especially in BPCA research, for the analysis of the frequency dependence of geffective, Tle, T2e, and the overall EPR line shape in frozen glasses and in room-temperature aqueous solutions. 

Pogni R, Baratto MC, Teutloff C et al (2006) A tryptophan neutral radical in the oxidized state of versatile peroxidase from Pleurotus eryngii a combined multi-frequency EPR and DFT study. J Biol Chem 281 9517-9526... 

Tje = multi-frequency EPR measurement of line widths geg = multi-frequency EPR measurement of geffectivel NMR = measurement of transverse relaxation of O H NMRD = measurement of proton Tj relaxation dispersion with relaxometer. 

The precise mechanistic detail of the enzymic reaction is not frilly understood, although a Ni -(H2) complex appears to be involved Crabtree and coworkers have published evidence for the first example of a Ni complex that interacts directly with H2, while Lubitz and coworkers have proposed using multi-frequency EPR analysis a reaction scheme for H2 and H+ interconversion at the biosite (see Scheme 15). ... 

Clarkson RB, Smirnov AI, Smirnova TI, Kang H, Belford RL, Earle K, Freed JH. 1998. Multi-frequency EPR determination of zero field splitting of high spin species in liquids Gd(III) chelates in water. Mol Phys 95 1325-1332. 

Multi Frequency EPR Spectroscepy of Conjugated Polymers and Their Nanocomposites... 

Title Multi frequency EPR spectroscopy of conjugated polymers and their nanocomposites / Victor 1. Krinichnyi. 

---