ETH Zürich, Department of Chemistry and Applied Bioscience, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.
Phys Chem Chem Phys. 2022 Oct 5;24(38):23517-23531. doi: 10.1039/d2cp03039j.
Relaxation-induced dipolar modulation enhancement (RIDME) time trace shapes reveal linear scaling with the proton concentration in homogeneous glassy samples. We describe here an approximate diffusion equation-based analysis of such data, which uses only two fit parameters and allows for global data fitting with good accuracy. By construction, the approach should be transferable to other pulse EPR experiments with longitudinal mixing block(s) present. The two fit parameters appear to be sensitive to the type of the glassy matrix and can be thus used for sample characterisation. The estimates suggest that the presented technique should be sensitive to protons at distances up to 3 nm from the electron spin at a 90% matrix deuteration level. We propose that a structural method might be developed based on such an intermolecular hyperfine (ih-)RIDME technique, which would be useful, for instance, in structural biology or dynamic nuclear polarisation experiments.
弛豫诱导偶极调制增强 (RIDME) 时间轨迹形状表明，在均匀玻璃状样品中与质子浓度呈线性比例关系。我们在这里描述了一种基于近似扩散方程的此类数据的分析方法，该方法仅使用两个拟合参数，并允许进行具有良好准确性的全局数据拟合。通过构造，该方法应该可以转移到具有纵向混合块的其他脉冲 EPR 实验中。这两个拟合参数似乎对玻璃基质的类型敏感，因此可以用于样品特性分析。这些估计表明，在 90%的基质氘化水平下，该技术应该能够检测到距离电子自旋 3nm 以内的质子。我们提出，基于这种分子间超精细（ih-）RIDME 技术，可以开发出一种结构方法，该方法在结构生物学或动态核极化实验中可能会很有用。
