Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich, Switzerland.
Faraday Discuss. 2022 Aug 25;236(0):461-484. doi: 10.1039/d1fd00108f.
Photoemission from submicrometer droplets containing a mixture of dioctyl phthalate and dioctyl sebacate was investigated by femtosecond and nanosecond photoionization. Photoelectron spectra recorded after ionization with single 4.7 eV femtosecond or nanosecond laser pulses showed marked differences between the two cases. These differences were attributed to ionization of long-lived states which only occurred within the duration of the nanosecond pulse. The tentative assignment of the long-lived states to dioctyl phthalate triplet states is discussed. A nanosecond-femtosecond pump-probe scheme using 4.7 eV (pump) and 3.1 eV (probe) pulses was used to investigate the decay dynamics of these long-lived states. The dynamics showed an accelerated decay rate at higher dioctyl phthalate concentrations. Furthermore, the dependence of the decay dynamics on droplet size and charge was investigated. The decay of the long-lived states was found to be faster in smaller droplets as well as in neutral droplets compared with both positively and negatively charged droplets. Possible mechanisms to explain these observations and the dominance of contributions from the droplets surface are discussed.
采用飞秒和纳秒光电离技术研究了含有邻苯二甲酸二辛酯和癸二酸二辛酯混合物的亚微米液滴的光发射。用单 4.7eV 飞秒或纳秒激光脉冲进行光离化后记录的光电子能谱在两种情况下显示出明显的差异。这些差异归因于仅在纳秒脉冲持续时间内发生的长寿命态的离化。将长寿命态暂定分配给邻苯二甲酸二辛酯三重态进行了讨论。使用 4.7eV（泵浦）和 3.1eV（探针）脉冲的纳秒-飞秒泵浦-探测方案用于研究这些长寿命态的衰减动力学。动力学显示在较高的邻苯二甲酸二辛酯浓度下具有更快的衰减速率。此外，还研究了衰减动力学对液滴尺寸和电荷的依赖性。与正电荷和负电荷液滴相比，较小的液滴以及中性液滴中的长寿命态的衰减更快。讨论了可能的机制来解释这些观察结果以及来自液滴表面的贡献的主导地位。
