High-field pulsed ENDOR

Raitsimring AM, Astashkin AV, Baute D, Goldfarb D, Poluektov OG, Lowe MP, Zech SG, Caravan P. 2006. Determination of the hydration number of gadolinium(III) complexes by high-field pulsed O ENDOR spectroscopy. ChemPhys Chem 7 1590-1597. 

Overlap of signals from different chemical elements is an inherent weakness of ENDOR spectroscopy at conventional ESR frequencies of 9.6 GHz (X band) as can be seen in Fig. 9. To overcome this problem, pulse ENDOR techniques have been developed that separate ENDOR signals according to the nuclear Zeeman frequency or the magnitude of the hyperfine couphng. Provided the hardware is available, high-field ENDOR provides a more simple alternative. At an ESR frequency of 95... 

For the MRI agents listed in Table 2 the values of D/gP are well within 100 mT. Therefore, the -1/2 o 1/2 EPR transition can be readily used for ENDOR measurements of these complexes at the. Bo > 3 T, which corresponds to the operational mw frequencies Vmw > 84 GHz (W-band). The analysis of the ENDOR spectra at such high-field conditions can be performed without taking account of the cfi. However, for most of the MRI agents even the Ka band (Bo 1 T, Dlg B < 0.1) pulsed ENDOR works reasonably well, although in this case it is better if the cfi corrections are taken explicitly into account in the numerical simulations. The... 

Radicals are formed in electron transfer reactions involving organic molecules such as chlorins [P, (bacterio)chlorophylls, (bacterio)pheophytins], quinones (Q, Q, A, of Type I RCs), tyrosine (TyrZ and TyrD in Photosystem II), carotenoids, etc. Classical EPR spectroscopy, now complemented by more elaborate techniques such as pulse EPR, ENDOR, or high-field EPR, is the most efficient way to study them (see examples of applications in References 3,4,14,42—45). 

Electrically-detected magnetic resonance has been used with Si P to sensitively probe nuclear spins with pulsed ENDOR at high and low magnetic fields/ High magnetic fields have been used to polarize Si P electron spins and this has been transferred to nuclear spins with optical excitation and entirely electrically/ As shown in Fig. 1, EDMR has been used to show that strain is useful for tuning Si P resonance frequencies. ... 

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