Shichao Sun, Bing Gu, Hang Hu, Lixin Lu, Diandong Tang, Vladimir Y Chernyak, Xiaosong Li, Shaul Mukamel
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引用次数: 0
摘要
通过检测穿过锥形交叉点时产生的电子相干性来直接探测光化学动力学是一项引人入胜的挑战。由于相干信号微弱,而且难以制备排除其他来源相干的纯激发波包,因此在实验上具有挑战性。我们建议使用时间分辨 X 射线磁圆二色性探测锥形交叉点周围的波包动态。磁场通过磁场响应各向异性放大了电子相干信号与群体信号的相对强度。更重要的是,由于通过锥形交叉点的激发态弛豫涉及到奇偶性的改变,磁耦合与电子相干的响应函数的对称性相匹配,使得相干信号只对锥形交叉点诱导的相干敏感,而排除了泵脉冲诱导的基态和激发态之间的相干。在这项理论研究中,我们将这种技术应用于吡咯分子的光解离动力学,并展示了它探测锥形交点电子相干以及种群转移的能力。我们证明了磁场可以有效地用于提取有关电子和核分子动力学的新信息。
Direct Probe of Conical Intersection Photochemistry by Time-Resolved X-ray Magnetic Circular Dichroism.
The direct probing of photochemical dynamics by detecting the electronic coherence generated during passage through conical intersections is an intriguing challenge. The weak coherence signal and the difficulty in preparing purely excited wave packets that exclude coherence from other sources make it experimentally challenging. We propose to use time-resolved X-ray magnetic circular dichroism to probe the wave packet dynamics around the conical intersection. The magnetic field amplifies the relative strength of the electronic coherence signal compared to populations through the magnetic field response anisotropy. More importantly, since the excited state relaxation through conical intersections involves a change of parity, the magnetic coupling matches the symmetry of the response function with the electronic coherence, making the coherence signal only sensitive to the conical intersection induced coherence and excludes the pump pulse induced coherence between the ground state and excited state. In this theoretical study, we apply this technique to the photodissociation dynamics of a pyrrole molecule and demonstrate its capability of probing electronic coherence at a conical intersection as well as population transfer. We demonstrate that a magnetic field can be effectively used to extract novel information about electron and nuclear molecular dynamics.
期刊介绍:
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