Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5407233 | Journal of Magnetic Resonance | 2008 | 5 Pages |
Abstract
By pulsed double electron-electron resonance (DEER), distances between spin labels in disordered systems up to 8Â nm can be measured. In addition, the relative orientation of the interacting radicals can be determined, provided that the bandwidth of the pulses is sufficiently small. On the other hand, the bandwidth has to exceed the dipolar interaction considerably, because otherwise the DEER modulations become distorted and the modulation depth decreases, making distance determination impossible. Therefore, small bandwidths, i.e. long pulses, place a lower limit on the distance that can be determined. Two new pulse sequences, observer-selective DEER (os-DEER) and dead-time free os-DEER, are introduced that make it possible to use long observer pulses with bandwidths that are smaller than the dipolar interaction. The new pulse sequences do not suffer from the distortions caused by the limited bandwidth of the observer pulses, as demonstrated by measurements on a nitroxide biradical. With observer pulses of 140Â ns, i.e., significantly longer than the 32Â ns used in the conventional DEER sequence, a dipolar interaction of 7.8Â MHz has been measured.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Sergey Milikisyants, Edgar J.J. Groenen, Martina Huber,