X-band rapid-scan EPR of nitroxyl radicals
X-band rapid-scan EPR of nitroxyl radicals
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DOI：
10.1016/j.jmr.2011.11.007
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发表时间：
2012-01-01
影响因子：
2.2
通讯作者：
Eaton, Gareth R.
中科院分区：
文献类型：
--
作者：
Mitchell, Deborah G.;Quine, Richard W.;Eaton, Gareth R.
获得了N-15-mHCTPO(4-hydro-3-carbamoyl-2，2，5，5-tetra-perdeuteromethyl-pyrrolin-1-N-15-oxyl-d(12))和N-15-(4-oxo-2，2，6，6-tetra-perdeuteromethyl-piperidinyl-N-15-oxyl-d(16)).的稀水溶液的X波段快速扫描电子顺磁共振波谱N-15-mHCTPO和N-15-PDT的光谱模拟与实验光谱符合得很好。在快速扫描模式下，随着扫描速率的增加，信号幅度与B-1线性增加的区域扩展到更高的功率，并且最大信号幅度增加。在快速扫描模式下，即使在只有4%的数据采集占空比的模式下获得快速扫描光谱，快速扫描光谱的信噪比也比未加宽的连续波EPR高约2倍。对于更高的占空比，预计每单位时间的信噪比将进一步提高。快速扫描光谱比连续波谱具有更高的带宽，因此在更快的扫描速率下需要更高的检测带宽。然而，当通过增加扫描频率来增加扫描速率时，来自检测带宽的噪声的增加由由于每单位时间的平均数目增加而导致的噪声的减少来补偿。由于信号带宽较高，快速扫描所需的谐振器Q比连续波低，因此快速扫描方法对于固有较低谐振器Q的有损样本是有利的。(C)2011 Elsevier Inc.保留所有权利。
X-band rapid-scan EPR spectra were obtained for dilute aqueous solutions of nitroxyl radicals N-15-mHCTPO (4-hydro-3-carbamoyl-2,2,5,5-tetra-perdeuteromethyl-pyrrolin-1-N-15-oxyl-d(12)) and N-15-PDT (4-oxo-2,2,6,6-tetra-perdeuteromethyl-piperidinyl-N-15-oxyl-d(16)). Simulations of spectra for N-15-mHCTPO and N-15-PDT agreed well with the experimental spectra. As the scan rate is increased in the rapid scan regime, the region in which signal amplitude increases linearly with B-1 extends to higher power and the maximum signal amplitude increases. In the rapid scan regime, the signal-to-noise for rapid-scan spectra was about a factor of 2 higher than for unbroadened CW EPR, even when the rapid scan spectra were obtained in a mode that had only 4% duty cycle for data acquisition. Further improvement in signal-to-noise per unit time is expected for higher duty cycles. Rapid scan spectra have higher bandwidth than CW spectra and therefore require higher detection bandwidths at faster scan rates. However, when the scan rate is increased by increasing the scan frequency, the increase in noise from the detection bandwidth is compensated by the decrease in noise due to increased number of averages per unit time. Because of the higher signal bandwidth, lower resonator Q is needed for rapid scan than for CW, so the rapid scan method is advantageous for lossy samples that inherently lower resonator Q. (C) 2011 Elsevier Inc. All rights reserved.