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A Study of the Exchange‐Determined Absorption Lineshape Outside the Lorentzian Region
Author(s) -
Cusumano C.,
Troup G. J.
Publication year - 1974
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.2220650224
Subject(s) - spins , exponential function , ferromagnetism , absorption (acoustics) , condensed matter physics , spin (aerodynamics) , gaussian , polystyrene , physics , electron paramagnetic resonance , absorption spectroscopy , line (geometry) , chemistry , quantum mechanics , atomic physics , materials science , nuclear magnetic resonance , mathematics , thermodynamics , optics , mathematical analysis , geometry , polymer
The wings of the EPR absorption line of an exchange narrowed spin system have been studied experimentally and theoretically. Solid solutions of DPPH in polystyrene with spin concentrations about 3 × 10 20 spins/cm 3 show an exponential rather than the often assumed Gaussian behaviour in the wings. The appropriate portion of the spectrum of the random frequency modulation causing the narrowing is recovered. The steepness of the exponential decrease is shown to be proportional to the exchange frequency. This result is in reasonable agreement with the high‐temperature spin correlation functions for a Heisenberg ferromagnet, obtained by some theoretical works on this subject.