Electron paramagnetic resonance spectrum

The electron spin resonance (ESR) spectrum of the radical anion of 1,10-phenanthroline obtained by reduction of 1,10-phenanthroline with sodium has been measured, and hyperfine splitting constants were assigned.116 

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More P J 1989 Analysis of polarized electron paramagnetic resonance spectra Advanced EPR Applications In Biology and Biochemistry ed A J Hoff (Amsterdam Elsevier) ch 12... 

Closs G L, Forbes M D E and Norris J R 1987 Spin-polarized electron paramagnetic resonance spectra of radical pairs in micelles. Observation of electron spin-spin interactions J. Phys. Chem. 91 3592-9... 

Tomkiewicz, M.A., Groen, A., and Cocivera, M. Electron paramagnetic resonance spectra of semiquinone intermediates observed during the photooxidation of phenol in water, J. Am. Chem. Soc., 93(25) 7102-7103,1971. 

Fig. 14.5 Electron paramagnetic resonance spectra (EPR) of lepidocrocite at RT, and after stepwise heating to various temperatures (Gehring Hofmeister, 1994 with permission).

Figure 13.19 Affinity chromatography with 2,2,6,6-tetiamethylpiperidine A-oxide (TEMPO)-/ mannose-functionalized dendrimers. Electron paramagnetic resonance spectra for one TEMPO/mannose experiment are shown.

F. S. Ham, Jahn-Teller effects in electron paramagnetic resonance spectra, in Electron Paramagnetic Resonance, edited by S. Geshwind, Plenum, New York, 1972, pp. 1-119. 

Figure 2. Electron paramagnetic resonance spectra of Mr bound to the single catalytic site on (Na + K )-ATPase. The X-hand spectrum (9.5 GHz) is shown in A, while the K-band spectrum (35 GHz) of the same complex is shown in B. The enzyme-Mn2 complex was centrifuged out of 20mM Tes-TMA, pH 7.5, and then combined with buffer so that the final concentrations were 0.15mM (Ha 4-K )-A TPase, 0.1 mM MnCl, 20mM Tes-TMA, pH 7.5. T = 23°C.

Table III. Electron Paramagnetic Resonance Spectra of Intermediates I-V...

Other peroxygen species can also be photolytically cleaved to yield the hydroxyl radical and another radical centre. For example, homolysis of peroxymonosulfate (HOOSO3) generates OH and SO4-. The concentration of the generated hydroxyl radical can be controlled by variation of the wavelength and the intensity used. The photolysis of hydrogen peroxide in the presence of alcohol produces EPR (electron paramagnetic resonance) spectra which indi-... 

Electron Paramagnetic Resonance Spectra. Only two of these complexes exhibit well-resolved EPR spectra. A narrow, isotropic signal observed at g = 2.005 for the trinuclear complex 12 at low temperatures is consistent with an S = 1/2 ground state169), but a detailed description of the electronic properties of the complex remains to be developed. The [Fe(MoS4)2]3 ion shows a rhombic S = 3/2 EPR spectrum that is very solvent dependent and, under certain conditions, is somewhat similar in apperance to that of FeMo-com). For example, in frozen aqueous solution, the apparent g values are 5.3,2.6, and 1.7181). If complex 14 also proves to have an S = 3/2 ground state, a somewhat similar EPR spectrum at low temperature would be expected as well. 

Titanium(III) exchanged 3A zeolite can also split water according to Eyring and coworkers (18). Illumination with visible light causes the evolution of h rogen as evidenced by mass spectrometry. As with the silver system described above, the titanium 3A zeolite process is not catalytic and loses reversibility. A detailed report concerning the electron paramagnetic resonance spectra of the titanium(III) 3A zeolite system has also been recently reported (19). 

Fig. 2. Electron paramagnetic resonance spectra of wild-type and TID and T2D mutants of FetSp as indicated. Spectra were obtained at a microwave frequency of 9.5 GHz and 120 K. The samples were prepared in 25% v/v ethylene glycol/50mM MES buffer, pH 6.0. The instrument settings were constant with values as follows microwave power, lOmw modulation frequency, 100 kHz modulation amplitude, 10 G time constant, 0.02 s sweep time, 60 s (Hassett et al., 1998).

Depending on the wavelength of radiation used, irradiation of Co2(CO)g produces either CO dissociation (at 250 nm) or cleavage into Co(CO)4 radicals (at 360 nm). The radical Co(CO)4 (2) itself has been detected by its Raman, infrared, UV-vis, and EPR see Electron Paramagnetic Resonance) spectra. It can be found by EPR when (1) is heated and sublimed on a 77 K cold finger in the EPR cavity, or it can be generated in a matrix at low temperature either by photolysis of (1) or by the metal vapor technique see Metal Vapor Synthesis of Transition Metal Compounds). 

The paramagnetism of many lanthanide ions finds practical application in NMR shift reagents and, increasingly, in MRI contrast agents. EPR (see Electron Paramagnetic Resonance) spectra are only readily obtained from Gd +, with its ground state, as yet there has been little study of the effects of environment upon the spectra. 

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