Electron Spin Exchange Processes in Strongly Coupled Spin Triads

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• 作者：Matvey V. Fedin ; Sergey L. Veber ; Igor A. Gromov ; Victor I. Ovcharenko ; Renad Z. Sagdeev ; Elena G. Bagryanskaya
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：May 24, 2007
• 年：2007
• 卷：111
• 期：20
• 页码：4449 - 4455
• 全文大小：120K
• 年卷期：v.111,no.20(May 24, 2007)
• ISSN：1520-5215

文摘

The complexes of Cu²⁺ hexafluoroacetylacetonate with two pyrazol-substituted nitronyl nitroxides are thechoice systems to study the spin dynamics of strongly exchange-coupled spin triads. The large values ofexchange coupling (ca. 100 cm^-1) and high-resolution electron paramagnetic resonance (EPR) at Q- andW-bands (35 and 94 GHz) allowed us to observe and interpret specific characteristics of these systems. Anelectron spin exchange process has been found between different multiplets of the spin triad, which manifestsitself as a significant shift of the EPR line position with temperature. We propose that the spin exchangeprocess is caused by the modulation of exchange interaction between copper and nitroxides by lattice vibrations.The estimations of the rate of exchange process and model calculations essentially support the observedphenomena. The studied characteristics of strongly coupled spin triads explain previously obtained results,agree with literature, and should be accounted for in future investigations of similar spin systems.