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The University of Southampton
MagRes@SotonNews and Seminar Schedule

Limits of Nuclear Spin Singlet State Life Times Seminar

Time:
15:00 - 16:00
Date:
1 November 2017
Venue:
Building 27, room 2003

For more information regarding this seminar, please telephone Giuseppe Pileio on 02380 59 (2) 4160 or email g.pileio@soton.ac.uk .

Event details

Nuclear spin singlet states significantly extend the timescale that may be explored in an NMR experiment. Such long-lived states have a number of possible potential applications such as studying slow motional processes or applied in hyperpolarization experiments. Furthermore, the long life times would allow one to store polarization for an extended period of time for later use. Understanding the factors which limit the singlet lifetimes is crucial for further improvement of singlet NMR and development of compounds that can accommodate the longest-living spin states. Furthermore, the long lifetimes provide an opportunity to measure weak relaxation mechanisms. Recently, we have also come across an important complication in lifetime measurements, due to thermal convection and B1 inhomogeneity. During the long wait times in singlet lifetime measurements, the spins can travel to regions of slightly different B1 values, and thus receive less than perfect reconversion into observable states. In the extreme case, the spins can travel outside of the coil region. These effects can be mitigated by sample spinning, sample confinement and special pulse sequences. After carefully eliminating these effects as well as oxygen as a possible source for relaxation, a large unaccounted for mechanism remains, which may arise from spin internal motion. Based on our experimental and computational findings, it appears likely that this mechanism represents the hard limit of singlet life times in many molecules

Speaker information

Prof Alexej Jerschow, New York University.

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