Early reports of long-lived quantum beating signals in photosynthetic pigment-protein complexes were interpreted to suggest that electronic coherence benefits from protection by the protein, but many subsequent studies have suggested instead that vibrational or vibronic contributions are responsible for the observed signals. Here, we devised two 2D-spectroscopy methods to observe how each exciton is perturbed by its nuclear environment in a photosynthetic complex. The first approach simultaneously monitors each exciton's energy fluctuations over time to obtain its time-dependent electronic-nuclear interactions. The second method isolates evidence of coupled interexcitonic environmental motions. The techniques are validated with Nile Blue A and subsequently used on the Fenna-Matthews-Olson (FMO) complex. The FMO data reveal that each exciton experiences nearly identical spectral motion after excitation and that spectral motion of one excited exciton induces similar motion on unpopulated neighboring excitonic states. These synchronized and correlated spectral dynamics prolong coherences in the FMO complex after femtosecond excitation.

早期报道了光合作用色素-蛋白质复合物中长寿命量子跳动信号的报道表明，电子相干性得益于蛋白质的保护，但随后的许多研究表明，振动或振动作用是观察到的信号的原因。在这里，我们设计了两种二维光谱方法，以观察每个激子在光合作用中如何受到其核环境的干扰。第一种方法同时监视每个激子随时间的能量波动，以获得其随时间变化的电子-核相互作用。第二种方法隔离了耦合的兴奋间环境运动的证据。该技术已通过尼罗蓝A验证，随后用于Fenna-Matthews-Olson（FMO）复合系统。FMO数据显示，每个激子在激发后都会经历几乎相同的谱运动，并且一个激发的激子的谱运动会在未填充的邻近激子态上诱导相似的运动。飞秒激发后，这些同步且相关的光谱动力学可延长FMO复合物中的相干性。