Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach: 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene

Jimmy S. Hwang; Yahya T. Al-Janabi

doi:10.1016/S1386-1425(99)00238-3

Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach: 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene

Jimmy S. Hwang, Yahya T. Al-Janabi

King Fahd University of Petroleum & Minerals

Research output: Contribution to journal › Conference article › peer-review

5 Scopus citations

Abstract

EPR linewidth measurements of PD-Tempone in toluene at 1 (L-Band), 4 (S-Band), 9 (X-Band) and 34 GHz (Q-Band) microwave frequencies indicate the presence of a distribution of relaxation times. The empirical response parameter introduced by Cole-Davidson for the analysis of dielectric relaxation in liquids has been used for the analysis of EPR relaxation data in the low frequency region. The Cole-Davidson parameter can assume values in the range 0<β≤1 when β = 1, one obtains the Debye-type spectral density. The calculated linewidth data at 1 GHz agrees with a Cole-Davidson distribution function with a width parameter 0.83±0.04 for a spherical solute. β<1 at L-band suggests the presence of an asymmetrical distribution of relaxation times associated with different modes of relaxation mechanisms or internal molecular motions. This study shows EPR experiments at low microwave frequencies are more sensitive to the shape of the correlation function.

Original language	English
Pages (from-to)	273-284
Number of pages	12
Journal	Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume	56
Issue number	2
DOIs	https://doi.org/10.1016/S1386-1425(99)00238-3
State	Published - 1 Feb 2000

Bibliographical note

Funding Information:
This work was inspired in part by a conversation one of us (JSH) had with Professor Daniel Kivelson. The authors would like to thank King Fahd University of Petroleum and Minerals for support of this research.

ASJC Scopus subject areas

Analytical Chemistry
Atomic and Molecular Physics, and Optics
Instrumentation
Spectroscopy

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10.1016/S1386-1425(99)00238-3

Cite this

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title = "Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach: 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene",

abstract = "EPR linewidth measurements of PD-Tempone in toluene at 1 (L-Band), 4 (S-Band), 9 (X-Band) and 34 GHz (Q-Band) microwave frequencies indicate the presence of a distribution of relaxation times. The empirical response parameter introduced by Cole-Davidson for the analysis of dielectric relaxation in liquids has been used for the analysis of EPR relaxation data in the low frequency region. The Cole-Davidson parameter can assume values in the range 0<β≤1 when β = 1, one obtains the Debye-type spectral density. The calculated linewidth data at 1 GHz agrees with a Cole-Davidson distribution function with a width parameter 0.83±0.04 for a spherical solute. β<1 at L-band suggests the presence of an asymmetrical distribution of relaxation times associated with different modes of relaxation mechanisms or internal molecular motions. This study shows EPR experiments at low microwave frequencies are more sensitive to the shape of the correlation function.",

author = "Hwang, \{Jimmy S.\} and Al-Janabi, \{Yahya T.\}",

note = "Funding Information: This work was inspired in part by a conversation one of us (JSH) had with Professor Daniel Kivelson. The authors would like to thank King Fahd University of Petroleum and Minerals for support of this research. ",

year = "2000",

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doi = "10.1016/S1386-1425(99)00238-3",

language = "English",

volume = "56",

pages = "273--284",

journal = "Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy",

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}

Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach: 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene. / Hwang, Jimmy S.; Al-Janabi, Yahya T.
In: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, Vol. 56, No. 2, 01.02.2000, p. 273-284.

Research output: Contribution to journal › Conference article › peer-review

TY - JOUR

T1 - Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach

T2 - 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene

AU - Hwang, Jimmy S.

AU - Al-Janabi, Yahya T.

N1 - Funding Information: This work was inspired in part by a conversation one of us (JSH) had with Professor Daniel Kivelson. The authors would like to thank King Fahd University of Petroleum and Minerals for support of this research.

PY - 2000/2/1

Y1 - 2000/2/1

N2 - EPR linewidth measurements of PD-Tempone in toluene at 1 (L-Band), 4 (S-Band), 9 (X-Band) and 34 GHz (Q-Band) microwave frequencies indicate the presence of a distribution of relaxation times. The empirical response parameter introduced by Cole-Davidson for the analysis of dielectric relaxation in liquids has been used for the analysis of EPR relaxation data in the low frequency region. The Cole-Davidson parameter can assume values in the range 0<β≤1 when β = 1, one obtains the Debye-type spectral density. The calculated linewidth data at 1 GHz agrees with a Cole-Davidson distribution function with a width parameter 0.83±0.04 for a spherical solute. β<1 at L-band suggests the presence of an asymmetrical distribution of relaxation times associated with different modes of relaxation mechanisms or internal molecular motions. This study shows EPR experiments at low microwave frequencies are more sensitive to the shape of the correlation function.

AB - EPR linewidth measurements of PD-Tempone in toluene at 1 (L-Band), 4 (S-Band), 9 (X-Band) and 34 GHz (Q-Band) microwave frequencies indicate the presence of a distribution of relaxation times. The empirical response parameter introduced by Cole-Davidson for the analysis of dielectric relaxation in liquids has been used for the analysis of EPR relaxation data in the low frequency region. The Cole-Davidson parameter can assume values in the range 0<β≤1 when β = 1, one obtains the Debye-type spectral density. The calculated linewidth data at 1 GHz agrees with a Cole-Davidson distribution function with a width parameter 0.83±0.04 for a spherical solute. β<1 at L-band suggests the presence of an asymmetrical distribution of relaxation times associated with different modes of relaxation mechanisms or internal molecular motions. This study shows EPR experiments at low microwave frequencies are more sensitive to the shape of the correlation function.

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DO - 10.1016/S1386-1425(99)00238-3

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JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

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Frequency dependent study of the correlation functions in EPR spectroscopy - the Cole-Davidson approach: 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene

Abstract

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