We have presented a model for analyzing polarization transfer via the thermal mixing dynamic nuclear polarization (DNP) mechanism at high magnetic field strengths that accounts for electron-electron cross-relaxation within an inhomogeneously broadened EPR line and have applied this model to simulate DNP and ELDOR experiments in the 4-amino TEMPO/water/glycerol system. These studies indicate that the 40 mM 4-amino TEMPO EPR line is in the intermediate cross-relaxation regime. Thus, the three-bath thermal mixing model, used previously to describe low field experiments, does not adequately explain the.polarization dynamics of the system at high fields. Given some basic parameters, such as the EPR line shape and spinlattice relaxation times, the model developed here can be used to predict the efficiency of DNP at even higher magnetic field strengths, where thermal mixing will be more severely attenuated due to the greater spectral dispersion and hence slower cross-relax ation rate , and with polarization agents other than the 4-amino TEMPO radical. Using this approach, it may be possible to develop optimal paramagnetic systems for performing DNP under experimental conditions suited for solid-state NMR studies of biological samples.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR000995-24
Application #
6118660
Study Section
Project Start
1999-05-15
Project End
2000-04-30
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
24
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Type
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
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