Khriachtchev Leonid, Lignell Antti, Juselius Jonas, Räsänen Markku, Savchenko Elena
Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
J Chem Phys. 2005 Jan 1;122(1):14510. doi: 10.1063/1.1827592.
Noble-gas hydride molecules with the general formula HNgY (Ng denotes noble-gas atom and Y denotes electronegative fragment) are usually prepared in solid noble gases. In many cases, the matrix-isolated HNgY molecules show a characteristic structure of the H-Ng stretching absorption: A close doublet as the main spectral feature and a weaker satellite at higher energy. This characteristic band structure is studied here for matrix-isolated HXeBr and HKrCl molecules. Based on the experimental and theoretical results, we suggest a model explaining the common features of the band structure of the HNgY molecules in noble-gas matrices. In this model, the main doublet bands are attributed to matrix sites where the splitting is caused by specific interactions of the embedded molecule with noble-gas matrix atoms in certain local morphology. The weaker blueshifted band is probably a fingerprint of hindered rotation (libration) of the embedded molecule in the lattice. This librational band has a mirror counterpart at lower energies appearing at higher matrix temperatures. Our present ab initio calculations for the one-to-one Xe...HXeBr complexes and the simulation of hindered rotation in a matrix support this image.
通式为HNgY（Ng表示稀有气体原子，Y表示电负性片段）的稀有气体氢化物分子通常在固态稀有气体中制备。在许多情况下，基质隔离的HNgY分子显示出H-Ng伸缩吸收的特征结构：一个紧密的双峰作为主要光谱特征，以及在较高能量处的较弱卫星峰。本文研究了基质隔离的HXeBr和HKrCl分子的这一特征能带结构。基于实验和理论结果，我们提出了一个模型来解释稀有气体基质中HNgY分子能带结构的共同特征。在这个模型中，主要的双峰带归因于基质位点，其中分裂是由嵌入分子与某些局部形态的稀有气体基质原子的特定相互作用引起的。较弱的蓝移带可能是晶格中嵌入分子受阻旋转（摆动）的指纹。这个摆动带在较低能量处有一个镜像对应物，出现在较高的基质温度下。我们目前对一对一的Xe...HXeBr配合物的从头算计算以及基质中受阻旋转的模拟支持了这一图像。
