Mett Richard R, Hyde James S
Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226-0509, USA.
J Magn Reson. 2003 Nov;165(1):137-52. doi: 10.1016/s1090-7807(03)00275-1.
An analytic solution of the Maxwell equations for aqueous flat cells in rectangular TE(102) cavities has led to the prediction of significant (3-6 times) X-band EPR signal improvement over the standard flat cell for a new sample configuration consisting of many flat cells oriented perpendicular to the electric field nodal plane. Analytic full wave solutions in the presence of sample and wall losses have been obtained and numerically evaluated. Observation of the predicted fields led to a classification of three distinct types of sample loss mechanisms, which, in turn inspired sample designs that minimize each loss type. The resulting EPR signal enhancement is due to the presence and centering of a tangential electric field node within each individual sample region. Samples that saturate with the available RF magnetic field and those that do not are considered. Signal enhancement appears in both types. These observations, done for the TE(102) mode, carry over to the uniform field (UF) modes, a relatively new class of microwave cavities for use in EPR spectroscopy developed in this laboratory. Rectangular UF modes have an RF magnetic field magnitude that is uniform in a plane. Based on this analysis, a practical multiple flat-cell design is proposed.
对矩形TE(102)腔中水性扁平样品池的麦克斯韦方程组进行解析求解，得出预测结果：对于一种由许多垂直于电场节点平面排列的扁平样品池组成的新样品配置，其X波段电子顺磁共振（EPR）信号比标准扁平样品池有显著（3至6倍）改善。已获得并对存在样品和壁损耗情况下的解析全波解进行了数值评估。对预测场的观察导致对三种不同类型的样品损耗机制进行了分类，这反过来又启发了使每种损耗类型最小化的样品设计。由此产生的EPR信号增强归因于每个单独样品区域内切向电场节点的存在及其居中。考虑了在可用射频磁场下饱和的样品和未饱和的样品。两种类型的样品都出现了信号增强。这些针对TE(102)模式的观察结果适用于均匀场（UF）模式，UF模式是本实验室开发的用于EPR光谱学的一类相对较新的微波腔。矩形UF模式在一个平面内具有均匀的射频磁场强度。基于此分析，提出了一种实用的多扁平样品池设计。
