The rotation-vibration structure of the SO2 C̃(1)B2 state explained by a new internal coordinate force field.
The rotation-vibration structure of the SO2 C̃(1)B2 state explained by a new internal coordinate force field.
复制标题
新的内坐标力场解释了SO2 C̃(1)B2态的旋转振动结构。
作者：
Jun Jiang;G. B. Park;R. Field
基于S（16）O2和S（18）O2的高分辨数据，导出了SO 2C_（1）B_2态的一个新的四次力场.其中包括本系列第一篇文献[G. B。Park等人，J. Chem.Phys.144，144311（2016）]。许多实验观测值不包括在拟合，如Franck-Condon强度和科里奥利扰动的有效C旋转常数的高度非谐C π态振动能级，很好地再现使用我们的力场。由于两个伸缩模的C π态是强耦合通过费米-133相互作用，C π态的振动结构进行了分析，在费米系统基组，明确地构建在这项工作中通过部分对角化的振动哈密顿量。根据Kellman和Xiao [J.Chem.Phys.93，5821（1990）]对费米共振体系的研究，从半经典动力学的角度讨论了费米体系基的物理意义。通过对费米体系基中的振动哈密顿量对角化，可以明确地确定所有振动能级的振动特征。它表明，弯曲模式不能单独处理的耦合拉伸模式，特别是在振动能量超过2000 cm（-1）。在此基础上，讨论了SO_2分子C ~+态的Coriolis相互作用的结构。我们确定了在破缺模式νβ（与我们的分配方案中的反对称伸缩模式相关）的振动级数中能级的有效C转动常数中交替模式的起源。
A new quartic force field for the SO2 C̃(1)B2 state has been derived, based on high resolution data from S(16)O2 and S(18)O2. Included are eight b2 symmetry vibrational levels of S(16)O2 reported in the first paper of this series [G. B. Park et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C̃ state vibrational levels, are well reproduced using our force field. Because the two stretching modes of the C̃ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C̃ state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and Xiao [J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm(-1). Based on our force field, the structure of the Coriolis interactions in the C̃ state of SO2 is also discussed. We identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, νβ (which correlates with the antisymmetric stretching mode in our assignment scheme).