Spectroscopic study on hydrogen-bonding and charge resonance interactions in aromatic cluser ions

本计画的目的是研究以芳香族分子为发色团的团簇中氢键的相互作用。我们研制了一套脉冲场电离ZEKE光电子能谱装置。中性团簇中的结构和氢键相互作用已经与那些在团簇阳离子的氢键相互作用与电荷共振相互作用的竞争进行了比较。我们观测了5-羟基酚酮-CO_2/H_2O和9-羟基非那烯酮-CO_2/H_2O团簇的电子光谱，并结合多维势计算阐明了分子间相互作用对质子隧穿的影响。在4-氨基苯甲腈-H_2O体系中，明确鉴定了三种结构异构体。已经成功地观察到了一种异构体的PFI-ZEKE光谱，其中水的氧原子与氨基质子形成氢键。我们研究了苯胺二聚体阳离子、苯-苯胺杂二聚体阳离子和苯-苯甲醇杂二聚体阳离子的稳定结构和分子间相互作用。在苯胺二聚体离子和苯-苯胺离子中，氢键相互作用占主导地位，没有发生电荷共振相互作用，而在苯-苯甲醇二聚体离子中观察到电荷共振相互作用。团簇离子中的分子间相互作用与从头算和密度泛函理论计算得到的稳定结构相关联。我们已经表明，氢键相互作用是非常敏感的电荷密度上的组成原子的发色团。

The purpose of this project is to investigate hydrogen bonding interaction in clusters involving an aromatic molecule as a chromophor. We have constructed an apparatus for pulsed field ionization (PFI)-ZEKE photoelectron spectroscopy. The structure and hydrogen bonding interaction in neutral clusters have been compared with those in cluster cations where the hydrogen bonding interaction competes with the charge resonance interaction. We have observed the electronic spectra of 5-hydroxytropolone-CO_2/H_2O and 9-hydroxyphenalenone-CO_2/H_2O clusters, and clarified the effects of intermolecular interaction on proton tunneling combined with multidimensional potential calculations. Three structural isomers have been clearly identified in 4-aminobenzonitrile-H_2O. The PFI-ZEKE spectrum of one isomer, where the oxygen atom of water is hydrogen-bonded to the amino proton, has been successfully observed. We have investigated stable structures and intermolecular interaction in the aniline dimer cation, benzene-aniline hetero-dimer cation, and benzene-benzylalcohol hetero-dimer cation. In the aniline dimer ion and benzene-aniline ion, the hydrogen-bonding interaction is predominant and no charge resonance interaction occurs, whereas the charge resonance interaction has been observed in the benzene-benzylalcohol dimer ion. The intermolecular interaction in the clusters ions has been correlated to the stable structures obtained by ab initio and density functional theory calculations. We have shown that the hydrogen bonding interaction is very sensitive to charge densities on the constitute atoms of the chromophor.