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ESR study of DMTM(TCNQ)₂ Kirui, Joseph Kiprono
Abstract
The ESR g-value and susceptibility measurements for DMTM(TCNQ)₂ have been studied as a function of angle made by crystal with magnetic field and temperature. The angular dependence of g-value is fitted to g² = α+βcos2θ - γsin2θ for three orthogonal directions of crystal rotation. The principal g-values are close to those expected for TCNQ compounds: g₁ = 2.0034, g₂ = 2.0030, g₃ = 2.0024. The susceptibility as a function of temperature agrees with bulk susceptibility measurements except that the maximum position occurs at about 30 K. The results of Oostra et al. for bulk susceptibility showed a maximum at around 50 K. The phase transition reported by Visser et al. at 272 K is observed in the ESR data as a 15% decrease in susceptibility. The linewidth is remarkably anisotropic typical of TCNQ salts. The phase transition study is done for two orientations of the crystal with the magnet field. In one of the orientations the linewidth narrows from 0.15 to 0.11 gauss and in the other it narrows from 0.24 to 0.18 gauss. In the former case there is a growth of a second line due to the twinned stack; transformation twinning takes place at the phase transition. A small level-crossing interaction is inferred from the change in relative intensities of the lines near the crossover.
Item Metadata
Title |
ESR study of DMTM(TCNQ)₂
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1990
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Description |
The ESR g-value and susceptibility measurements for DMTM(TCNQ)₂ have been studied as a function of angle made by crystal with magnetic field and temperature. The angular dependence of g-value is fitted to g² = α+βcos2θ - γsin2θ for three orthogonal directions of crystal rotation. The principal g-values are close to those expected for TCNQ compounds: g₁ = 2.0034, g₂ = 2.0030, g₃ = 2.0024. The susceptibility as a function of temperature agrees with bulk susceptibility measurements except that the maximum position occurs at about 30 K. The results of Oostra et al. for bulk susceptibility showed a maximum at around 50 K. The phase transition
reported by Visser et al. at 272 K is observed in the ESR data as a 15% decrease in susceptibility. The linewidth is remarkably anisotropic typical of TCNQ salts. The phase transition study is done for two orientations
of the crystal with the magnet field. In one of the orientations the linewidth narrows from 0.15 to 0.11 gauss and in the other it narrows from 0.24 to 0.18 gauss. In the former case there is a growth of a second line due to the twinned stack; transformation twinning takes place at the phase transition. A small level-crossing interaction is inferred from the change in relative intensities of the lines near the crossover.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-10-15
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085016
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.