E.S.R. of a one-dimensional Heisenberg antiferromagnet which undergoes a crystalline to discotic phase transition |
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| Authors: | M P Eastman Miin-Liang Horng B Freiha K W Sheu |
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| Institution: | Department of Chemistry , University of Texas at El Paso , El Paso, Texas, 79968, U.S.A. |
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| Abstract: | Abstract Single crystals and polycrystalline samples of the compounds bis(1,3-di(p-n-octylphenyl)propane-l,3-dionato)copper(II) I], and bis(l,3-di(p-n-octyloxy-phenyl)propane-l,3-dionato)copper(II) II] have been studied by E.S.R. The E.S.R. spectra of single crystals of I] at 298 K have the features associated with a spin 1/2 one-dimensional Heisenberg antiferromagnet while the spectra of single crystals of II] do not. E.S.R. of single crystals of I] and II] provides a reliable means of detecting previously reported crystalline to discotic phase transitions. Single crystals of I] heated beyond the temperature of the first discotic phase transition yield single line E.S.R. spectra which have an angular dependence and an asymmetric lineshape; these observations suggest that, in the discotic phase, exchange interactions are still significant and a degree of long range order is maintained. |
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