Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia.
Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
Int J Mol Sci. 2023 Jul 28;24(15):12122. doi: 10.3390/ijms241512122.
The effective dipole moment model for molecules of axial C3v symmetry is derived on the basis of the symmetry properties of a molecule which, on the one hand, is of the same order of efficiency (but much simpler and clearer in applications) as the analogous models derived on the basis of the irreducible tensorial sets theory, and, on the other hand, mathematically more correct in comparison with concepts like the Herman-Walles function used in the models. As an application of the general results obtained, we discuss high-resolution infrared spectra of CH335Cl, recorded with the Zürich prototype ZP2001 (Bruker IFS125 HR) Fourier transform infrared spectrometer at a resolution of 0.001 cm-1 and analyzed in the region of 880-1190 cm-1 (ν6 bending fundamental centered at ν0 = 1018.070790 cm-1). Absolute strengths of more than 2800 transitions (2081 lines) were obtained from the fit of their shapes both with Voigt and Hartmann-Tran profiles, and parameters of the effective dipole moment of the ν6 band were determined by the computer code SYMTOMLIST (SYMmetric TOp Molecules: LIne STrengths), created on the basis of a derived theoretical model. As the first step of the analysis of the experimental data, assignments of the recorded lines were made. A total of 5124 transitions with Jmax = 68, Kmax = 21 were assigned to the ν6 band. The weighted fit of 2077 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account different types of ro-vibrational effects in doubly degenerate vibrational states of the C3v-symmetric molecule. As the result, a set of 25 fitted parameters was obtained which reproduces the initial 2077 upper "experimental" ro-vibrational energy values with a root mean square deviation drms=4.7×10-5 cm-1. At the second step of the analysis, the computer code SYMTOMLIST was used for determination of the parameters of the derived effective dipole moment model. Six effective dipole moment parameters were obtained from the weighted fit procedure which reproduces absolute experimental strengths of the 2804 initial experimental transitions with a relative drms=3.4%.
基于分子的对称性质，推导出具有轴向 C3v 对称的分子的有效偶极矩模型。一方面，该模型在效率上与基于不可约张量集理论推导的类似模型相同（但在应用中更简单、更清晰），另一方面，与在模型中使用的 Herman-Walles 函数等概念相比，在数学上更加正确。作为获得的一般结果的应用，我们讨论了用苏黎世原型 ZP2001（Bruker IFS125 HR）傅里叶变换红外光谱仪在 0.001 cm-1 的分辨率下记录的 CH335Cl 的高分辨率红外光谱，在 880-1190 cm-1 （ν6 弯曲基频中心在 ν0 = 1018.070790 cm-1）的区域进行了分析。通过 Voigt 和 Hartmann-Tran 轮廓拟合它们的形状，获得了超过 2800 个跃迁（2081 条线）的绝对强度，并且通过基于推导的理论模型创建的计算机代码 SYMTOMLIST（对称拓扑分子：线强度）确定了 ν6 带的有效偶极矩参数。作为实验数据分析的第一步，对记录的线进行了分配。总共分配了 5124 个 Jmax = 68，Kmax = 21 的跃迁到 ν6 带。通过考虑到 C3v 对称分子的双重简并振动态中的不同类型的振转效应的哈密顿量，对从实验记录的跃迁中获得的 2077 个上能值进行了加权拟合。作为结果，获得了一组 25 个拟合参数，该组参数再现了初始 2077 个上“实验”振转能量值，均方根偏差 drms=4.7×10-5 cm-1。在分析的第二步中，使用计算机代码 SYMTOMLIST 确定导出的有效偶极矩模型的参数。通过加权拟合程序获得了六个有效偶极矩参数，该程序再现了 2804 个初始实验跃迁的绝对实验强度，相对均方根偏差 drms=3.4%。
