Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany.
J Chem Phys. 2013 Jun 28;138(24):244303. doi: 10.1063/1.4811199.
After almost two decades of high resolution molecular spectroscopy in superfluid helium droplets, the understanding of microsolvation is still the subject of intense experimental and theoretical research. According to the published spectroscopic work including microwave, infrared, and electronic spectroscopy, the latter appears to be particularly promising to study microsolvation because of the appearance of pure molecular transitions and spectrally separated phonon wings. Instead of studying the very details of the influence of the helium environment for one particular dopant molecule as previously done for phthalocyanine, the present study compares electronic spectra of a series of non-polar porphyrin derivatives when doped into helium droplets consisting of 10(4)-10(5) helium atoms. Thereby, we focus on the helium-induced fine structure, as revealed most clearly at the corresponding electronic origin. The interpretation and the assignment of particular features obtained in the fluorescence excitation spectra are based on additional investigations of dispersed emission spectra and of the saturation behavior. Besides many dopant-specific results, the experimental study provides strong evidence for a particular triple peak feature representing the characteristic signature of helium solvation for all seven related dopant species.
经过近二十年的超流氦液滴中高分辨率分子光谱研究，对微溶剂化的理解仍然是实验和理论研究的热点。根据已发表的包括微波、红外和电子光谱在内的光谱研究工作，由于出现了纯分子跃迁和光谱分离的声子翼，后者似乎特别适合研究微溶剂化。本研究不是像以前对酞菁那样研究特定掺杂分子在氦环境中的非常详细的影响，而是比较了当掺杂到由 10(4)-10(5)个氦原子组成的氦液滴中时，一系列非极性卟啉衍生物的电子光谱。因此，我们专注于氦诱导的精细结构，这在相应的电子起源处最为明显。荧光激发光谱中获得的特定特征的解释和分配是基于对分散发射光谱和饱和行为的进一步研究。除了许多特定掺杂剂的结果外，实验研究还为三个特征峰特征提供了有力证据，该特征峰代表了所有七种相关掺杂物种的氦溶剂化的特征标志。
