Pfeilsticker K, Lotter A, Peters C, Bosch H
Institut für Umweltphysik, INF 229, University of Heidelberg, D-69120 Heidelberg, Germany.
Science. 2003 Jun 27;300(5628):2078-80. doi: 10.1126/science.1082282.
Weakly bonded pairs of water molecules (H2O)2, or water dimers (WDs), may play an important role in photochemistry and climate, but the overlap of most of its spectral features with the water monomer (WM) has made detection difficult. We report on WD absorption measurements by means of atmospheric long-path (18.34 kilometers) differential optical absorption spectroscopy of the near-infrared OH stretching mode 0>f 4>b overtone transition predicted to be located near 746 nanometers. Our observation is in reasonable agreement with the known thermochemistry, calculated and measured structure, and spectroscopy (band strength, shape, and width) of the WD. The observation implies that the WD 0>f 4>b band is located at 749.5 nanometers, with a full width at half maximum of approximately 19.4 wave numbers, and that its band strength ranges between 1.23 x 10(-22) and 5.25 x 10(-22) centimeters per molecule.
弱键合的水分子对（H2O）2，即水二聚体（WDs），可能在光化学和气候中发挥重要作用，但它的大多数光谱特征与水单体（WM）重叠，使得检测变得困难。我们通过大气长路径（18.34公里）差分光学吸收光谱法，对预测位于746纳米附近的近红外OH伸缩模式0→4泛音跃迁进行了WD吸收测量。我们的观测结果与WD已知的热化学、计算和测量结构以及光谱（带强度、形状和宽度）合理一致。该观测结果表明，WD的0→4带位于749.5纳米处，半高全宽约为19.4波数，其带强度在每分子1.23×10^(-22)至5.25×10^(-22)平方厘米之间。
