Ultrafast Pump-Repump-Probe Photochemical Hole Burning as a Probe of Excited-State Reaction Pathway Branching.
Ultrafast Pump-Repump-Probe Photochemical Hole Burning as a Probe of Excited-State Reaction Pathway Branching.
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超快泵-再泵-探针光化学烧孔作为激发态反应路径分支的探针。
DOI：
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发表时间：
2018
影响因子：
5.7
通讯作者：
A. Bragg
中科院分区：
文献类型：
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作者：
Joshua A Snyder;A. Bragg
我们证明了泵浦-再泵浦-探测(PRP)瞬时烧孔作为一种光谱工具，用于区分由瞬时吸收光谱(TAS)观察到的激发光化学反应物的反应和非反应失活。这种方法利用一个延时的、波长可调的超快脉冲来改变被激发的反应物的数量，并通过光产物吸收的耗尽来量化“再泵浦”的影响。我们用这种方法表征了在266 nm激发下，邻三苯基(OTP)非绝热光环化反应生成S0二氢三苯(DHT)的动力学。TAS研究揭示了OTP*的双峰失活，但由于激发态光谱和产物光谱的重叠，两个驰豫时间尺度(700fS和3.0ps)都不能明确地归因于DHT的形成。PRP研究表明，S1OTP只在这些时间尺度中较慢的时间尺度上循环，较快的过程可归因于非反应性失活。我们证明，这种方法提供了更好的光化学洞察力，而不需要假设模型来全局拟合TAS收集的光谱瞬变。
We demonstrate pump-repump-probe (PRP) transient hole burning as a spectroscopic tool for differentiating reactive from nonreactive deactivation of excited photochemical reactants observed by transient absorption spectroscopy (TAS). This method utilizes a time-delayed, wavelength-tunable ultrafast pulse to alter the excited reactant population, with the impact of "repumping" quantified through depletions in photoproduct absorption. We apply this approach to characterize dynamics affecting the nonadiabatic photocyclization efficiency to form S0 dihydrotriphenylene (DHT) following 266 nm excitation of ortho-terphenyl (OTP). TAS studies revealed bimodal deactivation of OTP*, but neither relaxation time scale (700 fs and 3.0 ps) could be assigned unambiguously to DHT formation due to overlap of excited-state and product spectra. PRP studies reveal that S1 OTP only cyclizes on the slower of these time scales, with the faster process attributable to nonreactive deactivation. We demonstrate that this method offers greater photochemical insights without assuming models to globally fit spectral transients collected by TAS.
影响因子：
16.6
作者：
Guo, Xin;Zhou, Jiawang;Katz, Howard E.
通讯作者：
Katz, Howard E.