Determination of T₁-spin–lattice relaxation time in a two-level system by continuous wave multiquantum electron paramagnetic resonance spectroscopy in a presence of tetrachromatic microwave irradiation

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• 作者：Dutka ; Ma??gorzata ; Gurbiel ; Ryszard J. ; Kozio?? ; Jerzy ; Froncisz ; Wojciech
• 关键词：Continuous wave multiquantum electron paramagnetic resonance ; Multiphoton transitions ; Longitudinal relaxation time ; Nitroxide spin labels ; Inhomogeneous broadening
• 刊名：Journal of Magnetic Resonance
• 出版年：2004
• 出版时间：October, 2004
• 年：2004
• 卷：170
• 期：2
• 页码：220-227
• 全文大小：373 K

文摘

Applicability of continuous wave multiquantum EPR methods to study relaxation times at X-band is examined. Multiquantum transitions excited in a two-level system by tetrachromatic irradiation are used for these studies. The Bloch equation model is applied to simulate lineshapes of the three quantum transitions as a function of frequency difference between exciting fields. The dependence of multiquantum transition signals on relaxation times and microwave amplitude is shown. On this basis a method of deducing relaxation times from these signals is formulated. The case of a homogeneously and inhomogeneously broadened resonance line is considered. Two experimental methods are used to verify the proposed hypothesis: the X-band continuous wave multiquantum EPR with four frequencies microwave field and saturation recovery EPR. The values of T₁ obtained from CW MQ EPR and SR EPR are compared.