碱金属卤化物气相团簇的质谱与密度泛函理论研究

利用自制的电喷雾电离源与大气压力接口飞行时间质谱相结合，成功观察到了一系列的Cl^-(NaCl)_n和Br^-(NaBr)_m阴离子团簇．研究发现，Cl^-(NaCl)_n体系中n=4和7时质谱的相对丰度较高，被认为是幻数团簇，而其同系物Br^-(NaBr)_m，则发现了不同的质谱峰形，反映了这两种盐溶液在液相成核当中具有细微的差异．基于密度泛函理论的全局最小值搜索程序进一步验证了实验上的发现，显示出n=4和7时是最稳定的结构．另外对这类体系的能量计算发现它们的垂直解离能非常的高，即所谓的超级卤素

Sequential Observation of Alkali-halide Gas Phase Clusters in High Resolution TOF-MS and Prediction of Their Structures

Alkali halide clusters are interesting model systems that can provide information about how crystal properties evolve. To study these properties, a high-resolution atmospheric pressure inlet time-of-flight mass spectrometry (APi-TOF-MS) study of the sequential sodium halides series, Cl^-(NaCl)_n and Br^-(NaBr)_m, has been reported, and the viability of the APi-TOF-MS equipped with an electrospray ionization source in determining cluster compositions has been demonstrated. The isotopic patterns were well resolved, as n=4 and 7 were determined to be the magic numbers for Cl^-(NaCl)_n clusters, which were particularly abundant in the mass spectra. A global minimum search based on density functional theory enabled basin hopping yield the most stable structures for the mentioned series. The structures exhibit several distinct motifs which can be roughly categorized as linear chain, rock salt, and hexagonal ring. This work provides an effective way to discover and elucidate the nonstoichiometry sodium halide clusters. These clusters possess very high vertical detachment energies and are generally called as superhalogens, which play important roles in chemistry because they are widely used in the synthesis of new classes of charge-transfer salts