An EPR study of the relaxation parameters of paramagnetic centres in polyacetylene

Pelekh, A.Ye.; Krinichnyi, V.I.; Brezgunov, A. Yu.; Ткаченко, Л. И.; Козуб, Г. И.

doi:10.1016/0032-3950(91)90048-u

Cited by 6 publications

(10 citation statements)

References 16 publications

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“…The inequalities ω m T 1 Ͼ 1 and ω m T 1 Ͻ 1 hold for cis-and trans-PA, respectively, 59 therefore their T 1 and T 2 values can be calculated by using Eq. 8 and 9, respectively.…”

Section: Relaxation and Dynamics Of Charge Carriersmentioning

confidence: 99%

High‐Field ESR Spectroscopy of Conductive Polymers

Krinichnyi¹

2006

Advanced ESR Methods in Polymer Research

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“…The inequalities ω m T 1 Ͼ 1 and ω m T 1 Ͻ 1 hold for cis-and trans-PA, respectively, 59 therefore their T 1 and T 2 values can be calculated by using Eq. 8 and 9, respectively.…”

Section: Relaxation and Dynamics Of Charge Carriersmentioning

confidence: 99%

High‐Field ESR Spectroscopy of Conductive Polymers

Krinichnyi¹

2006

Advanced ESR Methods in Polymer Research

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“…We have shown previously [6,8,9] that the principal components of the g-tensor of PCs in some conjugated polymers could be averaged due to PCs moving at the rate V0D /> (gx --gz)flHo/h [13]. So PCs of two types with approximately equal magnetic parameters exist in PTFF; these are polarons moving along the polymer X-axis with a rate of v~ 5 9 109 s -1 and polarons pinned on the short polymer chain segments (Fig.…”

Section: Nature and Composition Of Pcs In The Pttfmentioning

confidence: 88%

“…The linewidth of mobile polarons, AH~~ b, in this case increases at 270 K from 10 to 11.2 and then to 175 G, respectively. Note, that whereas the spectral width of some conductive polymers increases nearly quadratically in the whole range of 9.5 GHz ~< v e ~< 140 GHz [6,8,9], the linewidth of both types of PCs in PTTF increases quadratically only in the 37 GHz ~< v e ~< 140 GHz frequency region. This will be discussed in terms of non-interacting spin-packets in the next Section.…”

Section: Nature and Composition Of Pcs In The Pttfmentioning

confidence: 94%

“…The setting of the microwave field and the a.c. modulation phases was made on a (DBTTF)3PtBr 6 single crystal as an extemal standard (see [8]). This standard was also used to measure the PC concentration.…”

Section: Methodsmentioning

confidence: 99%

“…The spin-lattice relaxation time T 1 in conjugated polymers behaves usually like T -2 at temperatures above 20 K [8,9,19,20]. Such behavior, at relatively high temperatures is explained by a Raman relaxation process in which two lattice phonons are involved.…”

Section: Passage Effects In Epr Spectra Of the Pttfmentioning

confidence: 99%

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Spin relaxation studies on conducting poly(tetrathiafulvalene)

et al. 1993

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Abstract. Magnetic parameters and the relaxation behavior of paramagnetic centers in ala iodine-doped poly(tetrathiafulvalene) semiconductor with a d.c. conductivity of 10 -5 S" cm -1 have been studied using mainly the 2 mm waveband EPR technique in the temperature range of 110-270 K. The EPR line shape analysis confirms the existence of immobile radicals pinned on short polymer chains and mobile polarons with different relaxation parameters in slightly doped poly(tetrathiafulvalene). The temperature dependences of electron spin-lattice and spin-spin relaxation times of paramagnetic centers of both types have been determined independently using the saturation method at the operation frequency v~ = 140 GHz. An anisotropic slow libration of immobile polarons with an activation energy of 0.02 eV have been registered for the first time using the saturation transfer EPR method. The temperature dependences of intrachain diffusion and interchain hopping rates in poly(tetrathiafulvalene) are determined from the T 1 and T 2 EPR data. The interchain spin dynamics is shown to correlate with libration of polarons trapped on polymer chains and is in good agreement with a hopping charge transport mechanism.

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Spin charge carrier dynamics in poly(bis-alkylthioacetylene)

2002

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Initial and laser-irradiated poly(bis-alkylthioacetylene) (PATAC) samples were investigated by electron paramagnetic resonance (EPR) at X-band (9.6 GHz), Q-band (37 GHz), and D-band (140 GHz) in a wide temperature range. Two types of paramagnetic centers were proved to exist in lasermodified polymer, namely, localized and mobile polarons with the concentration ratio and susceptibility depending on the irradiation dose and temperature. Superslow torsion motion of the polymer chains was studied by the saturation transfer method at D-band EPR. Additional information on the polymer chain segment dynamics was obtained by the spin probe method at X-band EPR. Spin-spin and spin-lattice relaxation times were measured separately by the steady-state saturation method at D-band EPR. Intrachain and interchain spin diffusion coefficients and conductivity arising from the polaron dynamics were calculated. It was shown that the polaron dynamics in laser-modified polymer is affected by the spin-spin interaction. The interchain charge transfer is stimulated by torsion motion of the polymer chains, whereas the total conductivity of irradiated PATAC is determined mainly by the dynamics of diamagnetic charge carriers. Magnetic, relaxation and dynamics parameters of PATAC were also shown to change during polymer storage.

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An EPR study of the relaxation parameters of paramagnetic centres in polyacetylene

Cited by 6 publications

References 16 publications

High‐Field ESR Spectroscopy of Conductive Polymers

High‐Field ESR Spectroscopy of Conductive Polymers

Spin relaxation studies on conducting poly(tetrathiafulvalene)

Spin charge carrier dynamics in poly(bis-alkylthioacetylene)

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