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The Model Hamiltonian and Some Properties of Magnetic Resonance of Triplet Excitons. I. Non‐Localized Exciton Approximation
Author(s) -
Berim G. O.,
Kessel A. R.
Publication year - 1976
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220760244
Subject(s) - exciton , electron paramagnetic resonance , spins , hamiltonian (control theory) , hyperfine structure , exchange interaction , condensed matter physics , paramagnetism , chemistry , resonance (particle physics) , molecule , pulsed epr , spectral line , physics , molecular physics , atomic physics , nuclear magnetic resonance , quantum mechanics , spin echo , magnetic resonance imaging , ferromagnetism , medicine , mathematical optimization , mathematics , radiology
A theoretical investigation is made of the magnetic resonance of triplet excitons (TE) inchains of molecules, each of them containing two paramagnetic spins S = 1/2 coupled by a strong exchange interaction ( I ) and by exchange ( K ≪ I ) with spins of neighbouring molecules. A Hamiltonian describing the appearance and interaction of unlocalized TE is proposed. The zone structure and wave functions of single‐exciton and bi‐exciton states are defined. It is shown that the considered model describes well the effects in electron paramagnetic resonance (EPR) spectrum which do not depend on temperature (nonexistence of hyperfine structure and of fine structure, caused by inequivalent positions of the molecules in the crystal). Qualitative estimations of the temperature behaviour of the EPR lines are made from the analysis of the bi‐excitonic states.