Dynamical Nuclear Polarization by Pulsed EPR Spectroscopy

林子生教授获实验物理化学计划资助，研究脉冲电子顺磁共振波谱的应用。该技术将用于研究从电子自旋到核自旋的自旋极化转移机制（动态核极化过程），该过程调用了有机固体的光激发三重态。将从三个方面进行研究：通过集成固体效应的共振极化转移，通过自旋锁定实验的相干极化转移，以及在能级反交叉区域的电子-核交叉极化动力学。这些研究的结果有望为共振极化传递和交叉极化过程的一般理论的形成提供信息。在某些有机固体中，质子核磁共振信号的增强可高达正常信号的1.5万倍。质子信号强度的如此大的改进可以使在这些晶体中低浓度的客体分子结构的研究成为可能。

Professor T.S. Lin is supported by a grant from the Experimental Physical Chemistry Program for the application of pulsed electron paramagnetic resonance spectroscopy. This technique will be used to study the mechanisms of spin polarization transfer from electron spins to nuclear spins (Dynamic Nuclear Polarization processes) which invoke the photo-excited triplet states of organic solids. Three aspects will be investigated: resonance polarization transfer via the integrated solid effect, coherent polarization transfer via the spin locking experiment, and electron-nuclear cross polarization dynamics at the level anticrossing region. The results of these studies are expected to provide the information which will allow formulation of a theory of the resonance polarization transfer and the cross polarization processes in general. %%% The enhancement of the proton nuclear magnetic resonance signal in some organic solids can be as high as a factor of 15,000 compared to the normal signal. Such a large improvement in the intensities of the proton signals could allow the studies of structures of guest molecules at low concentrations in these crystals.