Effect of Lanthanide and Cobalt Ions on Electron Spin Relaxation of Tempone in Glassy Water:Glycerol at 20 to 200 K


如何引用文章

全文:

开放存取 开放存取
受限制的访问 ##reader.subscriptionAccessGranted##
受限制的访问 订阅存取

详细

The enhancement of X-band spin–lattice and spin–spin relaxation rates for the nitroxide tempone (2,2,6,6-tetramethyl-4-oxo-piperidin-1-oxyl) in 1:1 water:glycerol by Dy3+, Er3+, Tm3+ or Co2+ was examined between 20 and 200 K. Nitroxide relaxation rates were measured by two-pulse spin echo and three-pulse inversion recovery. The impact of the rapidly relaxing metal aquo ions on 1/T1 of the nitroxide increases in the order Co2+ ~ Er3+ < Dy3+ < Tm3+. The maximum spin–lattice relaxation enhancement occurs at about 35 K for Dy3+, 40 K for Er3+, and 60 K for Co2+. When the metal ion is bound to the chelator diethylenetriamine pentaacetic acid (DTPA) the maximum enhancements for Dy(DTPA)2− and Er(DTPA)2− shift to about 80 K. The maximum enhancement is proposed to occur when 1/T1 for the metal ion is approximately equal to the resonance frequency for the nitroxide. Interaction with the paramagnetic metal ion causes a much larger fractional change in 1/T1 than for 1/T2. Below about 20 K the enhancement of nitroxide 1/T2 increases, which is attributed to relaxation of the metal ions at rates comparable to the electron–electron dipolar coupling, expressed in frequency units.

作者简介

Priyanka Aggarwal

Department of Chemistry and Biochemistry, University of Denver

Email: geaton@du.edu
美国, Denver, CO, 80210

Sandra Eaton

Department of Chemistry and Biochemistry, University of Denver

Email: geaton@du.edu
美国, Denver, CO, 80210

Gareth Eaton

Department of Chemistry and Biochemistry, University of Denver

编辑信件的主要联系方式.
Email: geaton@du.edu
美国, Denver, CO, 80210

补充文件

附件文件
动作
1. JATS XML

版权所有 © Springer-Verlag Wien, 2016