Light-generated nuclear quantum beats: a signature of photosynthesis.

Light-induced radical pairs in deuterated and deuterated plus 15N-substituted Synechococcus lividus cyanobacteria have been studied by transient EPR following pulsed laser excitation. Nuclear quantum beats are observed in the transverse electron magnetization at lower temperatures. Model calculations for the time profiles, evaluated at the high-field emissive maximum of the spectrum, indicate assignment of these coherences to nitrogen nuclei in the primary donor. Thorough investigation of the nuclear modulation patterns can provide detailed information on the electronic structure of the primary donor, providing insight into the mechanism of the primary events of plant photosynthesis.

本研究采用脉冲激光激发后的瞬态电子顺磁共振（transient EPR）技术，对氘代以及氘代并经15N取代的淡紫聚球藻（Synechococcus lividus）蓝细菌中的光诱导自由基对展开了研究。在低温条件下，横向电子磁化强度中可观测到核量子拍现象。针对光谱高场发射峰处的时间演化曲线开展模型计算，结果表明此类相干信号源自原初电子供体中的氮核。对核调制模式进行深入探究，能够获取原初电子供体电子结构的详细信息，进而为阐明植物光合作用的原初反应机制提供重要理论洞见。