Department of Basic Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
J Chem Phys. 2011 Aug 14;135(6):064307. doi: 10.1063/1.3616047.
Pure rotational spectra of the sodium chloride-water complexes, NaCl-(H(2)O)(n) (n = 1, 2, and 3), in the vibronic ground state have been observed by a Fourier- transform microwave spectrometer coupled with a laser ablation source. The (37)Cl-isotopic species and a few deuterated species have also been observed. From the analyses of the spectra, the rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants of the Na and Cl nuclei were determined precisely for all the species. The molecular structures of NaCl-(H(2)O)(n) were determined using the rotational constants and the molecular symmetry. The charge distributions around Na and Cl nuclei in NaCl are dramatically changed by the complex formation with H(2)O. Prominent dependences of the bond lengths r(Na-Cl) on the number of H(2)O were also observed. By a comparison with results of theoretical studies, it is shown that the structure of NaCl-(H(2)O)(3) is approaching to that of the contact ion-pair, which is considered to be an intermediate species in the incipient solvation process.
通过傅里叶变换微波光谱仪与激光烧蚀源耦合，观测到处于振动态基态的氯化钠-水复合物（NaCl-(H2O)(n)，n=1、2 和 3）的纯旋转光谱。还观测到了（37）Cl 同位素物种和一些氘代物种。通过对光谱的分析，精确确定了所有物种的转动常数、离心扭曲常数和 Na 和 Cl 核的核四极矩耦合常数。利用转动常数和分子对称性确定了 NaCl-(H2O)(n)的分子结构。氯化钠与 H2O 形成复合物后，Na 和 Cl 原子核周围的电荷分布发生了显著变化。还观察到键长 r(Na-Cl)与 H2O 数量的显著依赖性。通过与理论研究结果的比较，表明 NaCl-(H2O)(3)的结构接近接触离子对，这被认为是初始溶剂化过程中的中间物种。
