Studies of dynamic nuclear polarization with nitroxides in aqueous solution
Studies of dynamic nuclear polarization with nitroxides in aqueous solution
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DOI：
10.1007/s00723-008-0118-4
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发表时间：
2008-08-01
影响因子：
1
通讯作者：
Bennati, M.
中科院分区：
文献类型：
--
作者：
Hoefer, P.;Carl, P.;Bennati, M.
在9.7GHz的电子抽运频率下，研究了不同实验条件下氮氧自由基克里思与水溶液中H-1质子之间的动态核极化效应.特别是，我们比较了N-14-4-羟基-TEMPO（TEMPO）与4-氧代-TEMPO，并评估了H-2和N-15同位素标记的效果。此外，我们测试了伴随照射的影响，两个电子顺磁共振（EPR）线与N-15标记的化合物。我们的研究结果表明，在EPR线宽的H-1和N-15标记和崩溃的超精细线的数量由于N-15取代的减少，导致最高的增强ε = -140以往任何时候都在文献中报道。在我们的实验条件下，两条超精细线上的伴随泵浦没有得到更高的增强。
The dynamic nuclear polarization effect between the nitroxide radical TEMPO and the H-1 protons of water solution was investigated at an electron pumping frequency of 9.7 GHz for different experimental conditions. In particular, we compared N-14-4-hydroxy-TEMPO (TEMPOL) with 4-oxo-TEMPO and evaluated the effect of H-2 and N-15 isotope labelling. Furthermore, we tested the effect of concomitant irradiation on both electron paramagnetic resonance (EPR) lines with the N-15-labelled compound. Our results show that the reduction in the EPR line width given by the H-1 and N-15 labelling and the collapse in the number of hyperfine lines due to N-15 substitution leads to the highest enhancement of epsilon = -140 ever reported in the literature. Concomitant pumping on two hyperfine lines does not give higher enhancements at our experimental conditions.