Attosecond charge migration is a periodic evolution of the charge density at specific sites of a molecule on a timescale defined by the energy intervals between the electronic states involved. Here we report the observation of charge migration in neutral silane (SiH₄) in 690 as, its decoherence within 15 fs and its revival after 40–50 fs, using X-ray attosecond transient-absorption spectroscopy. We observe the migration of charge as pairs of quantum beats with a characteristic spectral phase in the transient spectrum, in agreement with theory. The decay and revival of the degree of electronic coherence is found to be a result of both adiabatic and non-adiabatic dynamics in the populated Rydberg and valence states. The experimental results are supported by fully quantum-mechanical ab initio calculations that include both electronic and nuclear dynamics, which additionally support the experimental evidence that conical intersections can mediate the transfer of electronic coherence from an initial superposition state to another one involving a different lower-lying state.

阿秒电荷迁移是分子特定位点电荷密度的周期性演变，时间尺度由所涉及的电子态之间的能量间隔定义。在这里，我们报告了中性硅烷 (SiH ₄) 在 690 as 中，它在 15 fs 内退相干，在 40-50 fs 后恢复，使用 X 射线阿秒瞬态吸收光谱。我们观察到电荷迁移为瞬态光谱中具有特征光谱相位的成对量子节拍，这与理论一致。发现电子相干度的衰减和恢复是填充的里德伯态和价态中绝热和非绝热动力学的结果。实验结果得到了包括电子和核动力学在内的完全量子力学从头算计算的支持，这还支持了实验证据，即锥形交叉点可以调节电子相干性从初始叠加态到另一个涉及不同低-的叠加态的转移。说谎的状态。