Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan.
J Chem Phys. 2009 Nov 14;131(18):184304. doi: 10.1063/1.3257686.
Infrared (IR) spectroscopy based on vacuum-ultraviolet one-photon ionization detection was carried out to investigate geometric structures of neutral and cationic clusters of acetic acid: (CH(3)COOH)(2), CH(3)COOH-CH(3)OH, and CH(3)COOH-H(2)O. All the neutral clusters have cyclic-type intermolecular structures, in which acetic acid and solvent molecules act as both hydrogen donors and acceptors, and two hydrogen-bonds are formed. On the other hand, (CH(3)COOH)(2) (+) and (CH(3)COOH-CH(3)OH)(+) form proton-transferred structures, where the acetic acid moiety donates the proton to the counter molecule. (CH(3)COOH-H(2)O)(+) has a non-proton-transferred structure, where CH(3)COOH(+) and H(2)O are hydrogen-bonded. The origin of these structural differences among the cluster cations is discussed with the relative sizes of the proton affinities of the cluster components and the potential energy curves along the proton-transfer coordinate.
基于真空紫外单光子电离检测的红外（IR）光谱法被用于研究乙酸的中性和阳离子团簇的几何结构：（CH(3)COOH)(2)、CH(3)COOH-CH(3)OH 和 CH(3)COOH-H(2)O。所有中性团簇都具有环状的分子间结构，其中乙酸和溶剂分子既充当氢键的供体又充当氢键的受体，形成两个氢键。另一方面，（CH(3)COOH)(2)(+)和（CH(3)COOH-CH(3)OH)(+)形成质子转移结构，其中乙酸部分将质子捐赠给反离子。（CH(3)COOH-H(2)O)(+)具有非质子转移结构，其中 CH(3)COOH(+)和 H(2)O 形成氢键。通过比较团簇成分的质子亲和力的相对大小以及质子转移坐标上的势能曲线，讨论了这些阳离子团簇结构差异的起源。
