scholarly journals Spin-Temperature Model of Nuclear Dynamic Polarization Using Free Radicals

1968 ◽  
Vol 20 (9) ◽  
pp. 419-421 ◽  
Author(s):  
M. Borghini
Keyword(s):  
Free Radicals ◽  
Dynamic Polarization ◽  
Temperature Model ◽  
Spin Temperature ◽  
Nuclear Dynamic

Systematische Untersuchungen der dynamischen Protonenpolarisation in organischen Kristallen mit eingebauten Radikalzentren

1969 ◽  
Vol 24 (10) ◽  
pp. 1532-1541
Author(s):  
K. Grude ◽  
W. Müller-Warmuth
Keyword(s):  
Magnetic Field ◽  
Enhancement Factor ◽  
Electronic Transitions ◽  
Dynamic Polarization ◽  
Spin Temperature ◽  
Field Range ◽  
Stable Free Radical ◽  
Organic Systems ◽  
High Proton ◽  
Paramagnetic Centres

Abstract In order to produce high proton polarizations, several organic hydrocarbons have been doped with stable free radical molecules. Through the "solid state effect" a part of the electronic polarization in a magnetic field has been transferred to the protons of these materials. For this purpose, the "forbidden electronic transitions" of the combined electron-proton system have been saturated at about 37 GHz. The enhancement factor of the dynamic proton polarization was measured by pulsed NMR at 56 MHz. In phenanthrene with about 4 w.% bis-diphenylen-phenylallyl (BPA) a maximum polarization of 10.5% has been obtained at 1.5 °K and 13 200 gauss. This value may be increased by extending the temperature and magnetic field range. Systematic investigations in numerous organic systems have been carried out and have particularly yielded data on the frequency dependence and on the saturation behaviour of the enhancement curves. - Spin temperature theories of dynamic polarization have been considered to explain the results and to find possibilities for improving the polarization. In particular, the exchange interaction of the radicals and the distinction between relaxing and polarizing paramagnetic centres had to be taken into account.

Nuclear dynamic polarization of protons in diluted copper-tutton salts. II

Physica ◽  
1970 ◽  
Vol 50 (2) ◽  
pp. 289-307 ◽  
Author(s):  
W.Th. Wenckebach ◽  
T.J.B. Swanenburg ◽  
N.J. Poulis
Keyword(s):  
Dynamic Polarization ◽  
Tutton Salts ◽  
Nuclear Dynamic

Dynamic polarization of protons and fluorine nuclei in solutions of free radicals

1967 ◽  
Vol 13 (1) ◽  
pp. 27-36 ◽  
Author(s):  
R.A. Dwek ◽  
H.D.W. Hill ◽  
J.G. Kenworthy ◽  
D.F.S. Natusch ◽  
R.E. Richards
Keyword(s):  
Free Radicals ◽  
Dynamic Polarization

Nuclear dynamic polarization of protons in diluted Copper-Tutton salts. I

Physica ◽  
1970 ◽  
Vol 46 (2) ◽  
pp. 303-314 ◽  
Author(s):  
W.Th. Wenckebach ◽  
T.J.B. Swanenburg ◽  
N.J. Poulis
Keyword(s):  
Dynamic Polarization ◽  
Tutton Salts ◽  
Nuclear Dynamic
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