ausblenden:
Schlagwörter:
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Zusammenfassung:
The theory of optical nuclear polarization (ONP) as outlined in two earlier papers is extended and generalized to a description of the complete optical excitation cycle.
The effects of selective population and depopulation of all electronic and nuclear spin substates of the excited triplet state are considered as well as the influence of relaxation and cross relaxation processes. Two models are discussed in detail, one spin system composed to two electrons (total spin S = 1) and one proton (I =
), the other of two electrons and two protons. It is argued that for most cases of interest, i.e., sufficiently large magnetic fields (⪢ 10 G), a superposition of all two electron one proton systems gives a rather accurated result for the polarization in many proton molecular entity.
The model has been applied to the ONP results observed in pure phenazine single crystals. The numerical results reproduce the experimentally observed field and orientation dependence rather closely. The only open parameter needed is the ratio of the electronic relaxation rate and the overall triplet state decay rate.
