The development of artificial biomimetic systems with real-world applications relies on a profound understanding of all photophysical and photochemical processes taking place upon light absorption by a chromophoric unit. Efficient photoinduced charge separation in photosensitizers or specialized photocatalysts is the process triggering most of the chemical reactions in the production of solar fuels, and so its proper characterization is of utmost importance. In this work, we investigate photoinduced charge separation processes in a perfluorinated Zn-tetraphenylporphyrin photosensitizer (ZnF₂₀). Ascorbate and 1,4-diazabicyclo[2.2.2]octane (DABCO) are used as reversible electron donors for the nanosecond-resolved pump-probe experiments using both optical absorption and resonance Raman scattering as probes. Our results show that, in spite of similar charge separation efficiencies, the DABCO-containing system exhibits a much faster kinetics of the charge-separated state formation and decay. This is attributed to its inherent ability to coordinate to the metal center. Time-resolved resonance Raman measurements allow for the detection of vibrational modes specific to both the triplet excited state of ZnF₂₀ and to its reduced state, complementing transient absorption data to fully characterize the charge separation process.

中文翻译：

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跟踪全氟化锌-四苯基卟啉敏化剂中的光致电荷分离


具有实际应用的人工仿生系统的开发依赖于对发色单元吸收光时发生的所有光物理和光化学过程的深刻理解。光敏剂或专用光催化剂中的有效光致电荷分离是引发太阳能燃料生产中大多数化学反应的过程，因此其正确表征至关重要。在这项工作中，我们研究了全氟化锌-四苯基卟啉光敏剂（ZnF ₂₀ ）中的光致电荷分离过程。抗坏血酸和 1,4-二氮杂双环[2.2.2]辛烷 (DABCO) 用作纳秒分辨泵浦探针实验的可逆电子供体，使用光学吸收和共振拉曼散射作为探针。我们的结果表明，尽管电荷分离效率相似，但含有 DABCO 的系统表现出更快的电荷分离态形成和衰变动力学。这归因于其与金属中心协调的固有能力。时间分辨共振拉曼测量可以检测 ZnF ₂₀ 三重激发态及其还原态特有的振动模式，补充瞬态吸收数据以全面表征电荷分离过程。