Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B 12
Ultrafast XANES Monitors Femtosecond Sequential Structural Evolution in Photoexcited Coenzyme B 12
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超快 XANES 监测光激发辅酶 B 12 中的飞秒顺序结构演化
DOI：
10.1021/acs.jpcb.9b09286
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Kubarych, Kevin J.
中科院分区：
文献类型：
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作者：
Miller, Nicholas A.;Michocki, Lindsay B.;Konar, Arkaprabha;Alonso-Mori, Roberto;Deb, Aniruddha;Glownia, James M.;Sofferman, Danielle L.;Song, Sanghoon;Kozlowski, Pawel M.;Kubarych, Kevin J.
偏振X射线吸收近边结构（XANES）在钴K-边缘和宽带紫外-可见瞬态吸收被用来监测的激发态结构的辅酶B12（腺苷钴胺素）在第一皮秒激发后的顺序演变。初始状态的特点是低于100 fs的连续变化周围的中央钴。它们首先在与跃迁偶极子正交的y方向上极化，然后在沿跃迁偶极子的沿着x方向上极化50 fs。轴向粘合的扩张遵循约。200 fs的时间尺度，因为分子移出势能面的弗兰克-康登活性区。在相同的200 fs时间尺度上，存在导致受激发射损失和在340 nm处出现强吸收的电子变化。这些测量提供了一个钴为中心的电影的激发分子，因为它演变到本地激发态的最小值。
Polarized X-ray absorption near-edge structure (XANES) at the Co K-edge and broadband UV–vis transient absorption are used to monitor the sequential evolution of the excited-state structure of coenzyme B12(adenosylcobalamin) over the first picosecond following excitation. The initial state is characterized by sub-100 fs sequential changes around the central cobalt. These are polarized first in they-direction orthogonal to the transition dipole and 50 fs later in thex-direction along the transition dipole. Expansion of the axial bonds follows on a ca. 200 fs time scale as the molecule moves out of the Franck–Condon active region of the potential energy surface. On the same 200 fs time scale there are electronic changes that result in the loss of stimulated emission and the appearance of a strong absorption at 340 nm. These measurements provide a cobalt-centered movie of the excited molecule as it evolves to the local excited-state minimum.