Ito Fumiyuki, Hirabayashi Shinichi
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba-West, Onogawa 16-1, Tsukuba, Ibaraki 305-8569, Japan.
J Chem Phys. 2006 Jun 21;124(23):234509. doi: 10.1063/1.2206784.
We have observed infrared spectra of the CF(3)I dimer produced in a supersonic jet by matrix-isolation Fourier transform infrared spectroscopy and infrared cavity ring-down (IR-CRD) spectroscopy. In the matrix-isolation experiments, the dimer was isolated in an Ar matrix by the pulse-deposition method. The recorded spectral range covers the symmetric (nu(1)) and doubly degenerate (nu(4)) C-F stretching regions. From the concentration dependence of the matrix-isolation spectra we have assigned one dimer band for each fundamental region. It was not easy to identify the dimer band for the nu(4) band because of the multiplet feature of the monomeric nu(4) band caused by the site symmetry breaking. The spectra of (CF(3)I)(2) in the nu(4) band region were thus also measured in the gas phase by IR-CRD spectroscopy, where we detected two dimer bands. Comparing the observed band positions with the results of quantum chemical calculations, we have assigned the observed dimer bands to the head-to-head isomer. The structure of (CF(3)I)(2) and its photochemical implications are discussed, in comparison with methyl iodide dimer reported previously [Ito et al., Chem. Phys. Lett. 343, 185 (2001)].
我们通过基质隔离傅里叶变换红外光谱和红外腔衰荡（IR-CRD）光谱，观测了在超声速射流中产生的CF(3)I二聚体的红外光谱。在基质隔离实验中，通过脉冲沉积法将二聚体隔离在氩基质中。记录的光谱范围覆盖对称（ν(1)）和双重简并（ν(4)）的C-F伸缩振动区域。根据基质隔离光谱的浓度依赖性，我们为每个基频区域指定了一个二聚体谱带。由于单体ν(4)谱带因位点对称性破坏而具有多重峰特征，因此很难识别ν(4)谱带的二聚体谱带。因此，还通过IR-CRD光谱在气相中测量了（CF(3)I）(2)在ν(4)谱带区域的光谱，在那里我们检测到了两个二聚体谱带。将观测到的谱带位置与量子化学计算结果进行比较，我们将观测到的二聚体谱带指定为头对头异构体。与先前报道的甲基碘二聚体[Ito等人，《化学物理快报》343, 185 (2001)]相比，讨论了（CF(3)I）(2)的结构及其光化学意义。
