Asselin Pierre, Soulard Pascale, Madebène Bruno, Lewerenz Marius
Université Pierre et Marie Curie--Paris 6, CNRS Laboratoire Dynamique, Interactions et Réactivité, UMR 7075 Case 49, 4 Place Jussieu, 75252, Paris Cedex 05, France.
Phys Chem Chem Phys. 2007 Jun 14;9(22):2868-76. doi: 10.1039/b702824e. Epub 2007 Apr 16.
The rotationally resolved Fourier transform infrared (FTIR) spectrum of the nu(s) HCl and DCl stretching bands for the hydrogen bonded complex H2S-HCl and its isotopomer D2S-DCl have been observed in a supersonic jet at 0.02 cm(-1) resolution. In the same experimental conditions, two additional bands observed without rotational structure in the HCl range of the dimer have been assigned to the cyclic trimer H2S-(HCl)(2). The multidimensional coupling picture involving the donor stretch mode nu(s) and low frequency intermolecular modes already evidenced in several medium strength hydrogen bonded complexes is beautifully confirmed by the observation of completely separated hot band progressions in the 198 K cell spectrum of both dimers. Based on our anharmonic adiabatic approach for the treatment of the coupled vibrations, absolute vibrational frequencies, diagonal and off-diagonal anharmonicities as well as rovibrational coupling constants obtained from analyses of several 2-D subspaces at MP2 and CCSD(T) level are in excellent agreement with spectroscopic results. In the case of small light complexes, the combination of elevated rotational constants and a negligible contribution of intramolecular vibrational redistribution (IVR) improve the reliability of predissociation lifetime measurements, estimated to 180 ps for H2S-HCl and above 200 ps for D2S-DCl.
在分辨率为0.02 cm⁻¹的超音速喷流中观测到了氢键复合物H₂S - HCl及其同位素异构体D₂S - DCl的νₛ HCl和DCl伸缩带的转动分辨傅里叶变换红外（FTIR）光谱。在相同实验条件下，在二聚体的HCl范围内观测到的另外两个无转动结构的谱带被归属为环状三聚体H₂S - (HCl)₂。在几个中等强度氢键复合物中已经证实的涉及供体伸缩模式νₛ和低频分子间模式的多维耦合图景，通过在两个二聚体的198 K细胞光谱中观测到完全分离的热谱带序列得到了很好的证实。基于我们用于处理耦合振动的非谐绝热方法，从MP2和CCSD(T)水平的几个二维子空间分析中获得的绝对振动频率、对角和非对角非谐性以及振转耦合常数与光谱结果非常吻合。对于小的轻复合物，升高的转动常数和分子内振动再分布（IVR）的可忽略贡献的组合提高了预解离寿命测量的可靠性，估计H₂S - HCl为180 ps，D₂S - DCl超过200 ps。
