Document Detail


Electron spin relaxation in x-lithium phthalocyanine.
MedLine Citation:
PMID:  17583936     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Continuous-wave linewidths and spin susceptibilities, spin-spin relaxation rates (1/T2), and spin-lattice relaxation rates (1/T1) for two sources of x-LiPc were measured at 9.5 GHz between 15 and 298 K. Relaxation rates at 34 GHz were measured between 80 and 298 K. Room-temperature relaxation rates also were measured at 250 MHz, 1.9 GHz, and 2.76 GHz. The temperature dependences of linewidths and spin susceptibilities are characteristic of 1-D organic conductors. The ratio of populations of localized and delocalized electrons varies with sample preparation. For a single needle between 15 and about 200 K, 1/T2 is higher for the parallel orientation, but 1/T1 is higher for the perpendicular orientation, consistent with predictions based on dipolar interactions. Between about 60 and 150 K, which is the temperature regime in which spin susceptibility is changing rapidly with temperature, 1/T1 exhibits a non-monotonic dependence on temperature and is lower at 34 GHz than at 9.5 GHz. In other organic conductors, this dependence has been attributed to a bottleneck mechanism of relaxation. At higher temperatures, 1/T1 becomes less orientation-dependent. At room temperature, T1 increases rapidly between 250 MHz (3.0 micros) and 2.76 GHz (6.3 micros) and then shows less frequency dependence up to 34 GHz (9.8 micros). The relaxation rate near room temperature might have a substantial contribution from spin hopping perpendicular to the stacking axis of the molecules.
Authors:
Hideo Sato; Lauraine A Dalton; Duc Ha; Richard W Quine; Sandra S Eaton; Gareth R Eaton
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2007-06-21
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  111     ISSN:  1520-6106     ISO Abbreviation:  J Phys Chem B     Publication Date:  2007 Jul 
Date Detail:
Created Date:  2007-07-12     Completed Date:  2007-08-30     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7972-7     Citation Subset:  IM    
Affiliation:
Department of Chemistry and Biochemistry and Department of Engineering, University of Denver, Denver, Colorado 80208, USA.
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MeSH Terms
Descriptor/Qualifier:
Electrochemistry
Electron Spin Resonance Spectroscopy
Indoles / chemistry*
Organometallic Compounds / chemistry*
Spin Labels*
Temperature
Grant Support
ID/Acronym/Agency:
EB002034/EB/NIBIB NIH HHS; EB002807/EB/NIBIB NIH HHS
Chemical
Reg. No./Substance:
0/Indoles; 0/Organometallic Compounds; 0/Spin Labels; 111716-29-1/lithium phthalocyanine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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