中文摘要：

利用团簇模型研究了质子化水团簇对乙炔的溶剂化作用．H＋（C2H2）（H2O）n（n=1-5）的量子化学计算结果表明，水分子倾向与乙炔的π电子形成新型OHππ氢键作用，并且乙炔的第一溶剂层需要4个水分子来完成．模拟的红外光谱揭示了OH…π氢键作用后的OH伸缩振动是研究乙炔与水溶剂化过程的灵敏探针．这些红外光谱可以用红外光解离光谱实验方法测得，将为理解OH…π氢键作用以及质子化水团簇如何溶剂化乙炔提供有力的科学数据．关键词：乙炔，水，溶剂化，红外光解离光谱，量子化学计算.

英文摘要：

The effect of solvation on the conformation of acetylene has been studied by adding one water molecule at a time. Quantum chemical calculations of the n＋ （C2H2）（H2O）n （n=1-5） clusters indicate that the H2O molecules prefer to form the OH...Tr interaction rather than the CH...O interaction. This solvation motif is different from that of neutral （C2H2）（H2O）n （n=1-4） clusters, in which the H2O molecules prefer to form the CH...O and OH...C Hbonds. For the H＋（C2H2）（H2O）n cationic clusters, the first solvation shell consists of one ring structure with two OH...Tr H-bonds and three water molecules, which is completed at n=4. Simulated infrared spectra reveal that vibrational frequencies of OH... H-bonded O-H stretching afford a sensitive probe for exploring the solvation of acetylene by protonated water molecules. Infrared spectra of the H＋ （C2H2）（H2O）n （n=1-5） clusters could be readily measured by the infrared photodissociation technique and thus provide useful information for the understanding of solvation processes.