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Spectroscopic study of novel cluster structures created as chemical intermediates in supersonic molecular beams

超音速分子束中作为化学中间体产生的新型簇结构的光谱研究

基本信息

批准号：
20550005
负责人：
MIKAMI Naohiko
金额：
$ 3.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2010
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20550005/
关键词：
分子分光反応中間体構造解析芳香族求核置換反応中間体 σ-complex 分子クラスターベンゼン・メタノールクラスタープロトン付加水クラスターアセトン2量体光イオン化誘起異性化反応 C_6F_6・NH_3クラスターフォルムアミド・水クラスター水素結合形態変化水和メタノールクラスター HCP分子前期解離反応機構レーザー分光気相イオン反応制御

项目摘要

Spectroscopic studies on jet-cooled molecular cluster cations have been carried out for the following systems ;1. IR and electronic spectroscopy of [C_6H_6(NH_3)_n]^+ (n=1 and 2) revealed that their stable forms are of s-complex type, in which the ammonia moiety is covalently bonded to the benzene moiety as expected as the reaction intermediate of nucleophilic substitution of aromatics. The similar structures of [Benzene-(Methanol)_n]^+ (n=2, 3) were also investigated in combination with quantum chemical calculations.2. H-bond network structures of H^+(H_2O)_n (n=20-200) were investigated by IR spectroscopy. It was found that the spectral features of the clusters with increasing cluster size become similar to the characteristic features of water and of ice, indicating the network morphology of the large-size clusters transmutes gradually to those of the bulk systems. It was also found that the spectral feature depends on the internal energy in the species.3.Structures of neutral and cationic clusters of acetone and of acetic acid were investigated by using IR spectroscopy based on vacuum-ultraviolet one-photon ionization detection. It was found that the keto-enol transition is generated after the ionization for many clusters, such as their dimers, whereas their neutrals are of the keto-form. The isomerization mechanism was discussed in relation to their proton affinities and the potential surface of the proton-transfer coordinate.

射流冷却分子簇阳离子的光谱研究主要针对以下体系进行：1。[C_6H_6(NH_3)_n]^+ （n=1和2）的IR和电子能谱分析表明，它们的稳定形态为s-络合物，其中氨部分与苯部分共价键合，是芳烃亲核取代的反应中间体。结合量子化学计算，研究了[苯-（甲醇）_n]^+ (n= 2,3)的相似结构。用红外光谱研究了H^+(H_2O)_n （n=20 ~ 200）的氢键网络结构。研究发现，随着团簇大小的增加，团簇的光谱特征逐渐趋近于水和冰的特征特征，表明大团簇的网络形态逐渐向大团簇的网络形态转变。光谱特征与物种的内能有关。利用真空紫外单光子电离红外光谱研究了丙酮和乙酸的中性和阳离子簇的结构。研究发现，许多簇（如二聚体）电离后产生酮-烯醇过渡，而它们的中性物是酮-烯醇形式。讨论了它们的异构化机理与它们的质子亲和和质子转移座标的势面有关。