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Exact Treatment of the Coupled Coherent and Incoherent Motion of Triplet Excitons and Its Influence on the Lineshape of ESR
Author(s) -
Reineker P.
Publication year - 1972
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.2220520213
Subject(s) - exciton , hamiltonian (control theory) , physics , motion (physics) , incoherent scatter , coherent states , density matrix , equations of motion , line (geometry) , spin (aerodynamics) , condensed matter physics , atomic physics , quantum mechanics , scattering , classical mechanics , mathematics , mathematical optimization , geometry , quantum , thermodynamics
The motion of excitons is considered by a stochastic model comprising both its coherent and incoherent motion. The coherent motion is determined by the exchange interaction integral J whereas the incoherent motion is described by the strengths of local (γ 0 ) and non‐local (γ 1 ) fluctuations. The spin motion is described by the usual spin Hamiltonian of two differently oriented molecules. The equation of motion of the density matrix of the system is solved and the lineshapes of ESR are calculated for several sets of the above parameters by computer calculation. Especially, it is shown that the coherent motion too may lead to a single absorption line as previously obtained for incoherent exciton motion. Furtheron, it is inferred that the transition from coherent to incoherent exciton motion is determined mainly by the ratio of γ 0 and J and that γ 1 is a decisive quantity in the transition from the broadening of one or several ESR lines to the narrowing of a single line.