New Insights into the Charge-Transfer-to-Solvent Spectrum of Aqueous Iodide: Surface versus Bulk
New Insights into the Charge-Transfer-to-Solvent Spectrum of Aqueous Iodide: Surface versus Bulk
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DOI：
10.1021/acs.jpclett.9b03857
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发表时间：
2020-03-05
影响因子：
5.7
通讯作者：
Bradforth, Stephen E.
中科院分区：
文献类型：
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作者：
Bhattacharyya, Dhritiman;Mizuno, Hikaru;Bradforth, Stephen E.
液相电荷转移到溶剂(CTTS)的转变很重要，因为它们是通向溶剂化电子的光化学途径。本工作利用宽带深紫外光电子和频(DUV-ESFG)和双光子吸收(2PA)光谱技术对水中碘化合物CTTS在空气/水界面和体相溶液中的激发性质进行了指认和比较。在单光子吸收(1PA)谱中，激发类6S里德堡轨道(5p>；6s)产生一对自旋-轨道分裂碘态，即P-2(3/2)和P-2(1/2)。在2PA谱中，没有较低能的P-2(3/2)峰，观察到的2PA峰与1PA中的较高的P-2(1/2)CTTS峰相比蓝移了0.14 eV，这是由5p-gt；6p电子促进引起的。在ESFG谱中观察到的能带是由振动耦合和非对称界面溶剂化产生的外电场引起的5p-gt；6p和5p-gt；6s激发态的混合所致。
Liquid phase charge-transfer-to-solvent (CTTS) transitions are important, as they serve as photochemical routes to solvated electrons. In this work, broadband deep-ultraviolet electronic sum frequency generation (DUV-ESFG) and two-photon absorption (2PA) spectroscopic techniques were used to assign and compare the nature of the aqueous iodide CTTS excitations at the air/water interface and in bulk solution. In the one-photon absorption (1PA) spectrum, excitation to the 6s Rydberg-like orbital (5p -> 6s) gives rise to a pair of spin-orbit split iodine states, P-2(3/2) and P-2(1/2). In the 2PA spectra, the lower-energy P-2(3/2) peak is absent and the observed 2PA peak, which is similar to 0.14 eV blue-shifted relative to the upper P-2(1/2) CTTS peak seen in 1PA, arises from 5p -> 6p electronic promotion. The band observed in the ESFG spectrum is attributed to mixing of excited states involving 5p -> 6p and 5p -> 6s promotions caused by both vibronic coupling and the external electric field generated by asymmetric interfacial solvation.