Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
J Phys Chem A. 2009 Nov 5;113(44):12134-41. doi: 10.1021/jp9061187.
To investigate hydrogen bond network structures of tens of water molecules, we report infrared spectra of moderately size (n)-selected phenol-(H2O)n (approximately 10 < or = n < or = approximately 50), which have essentially the same network structures as (H2O)(n+1). The phenyl group in phenol-(H2O)(n) allows us to apply photoionization-based size selection and infrared-ultraviolet double resonance spectroscopy. The spectra show a clear low-frequency shift of the free OH stretching band with increasing n. Detailed analyses with density functional theory calculations indicate that this shift is accounted for by the hydrogen bond network development from highly strained ones in the small (n < approximately 10) clusters to more relaxed ones in the larger clusters, in addition to the cooperativity of hydrogen bonds.
为了研究数十个水分子的氢键网络结构，我们报告了中等大小（n）选择的苯酚-（H2O）n（约 10 < or = n < or = 约 50）的红外光谱，这些分子具有与（H2O）（n+1）基本相同的网络结构。在苯酚-（H2O）（n）中，苯基允许我们应用基于光致电离的尺寸选择和红外-紫外双共振光谱。光谱显示随着 n 的增加，游离 OH 伸缩带的低频位移明显。用密度泛函理论计算进行的详细分析表明，这种位移是由于氢键网络从较小（n < 约 10）团簇中的高度应变状态发展到较大团簇中的更松弛状态，以及氢键的协同作用所致。
