The rotation-vibration structure of the SO2 C1B2 state explained by a new internal coordinate force field
A new quartic force field for the SO2 $$\tilde{C}$$1B2 state has been derived, based on high resolution data from S16O2 and S18O2. Included are eight b2 symmetry vibrational levels of S16O2 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 $$\tilde{C}$$ state vibrational levels, are well reproduced using our force field. Because the two stretching modes of the $$\tilde{C}$$ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the $$\tilde{C}$$ 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 $$\tilde{C}$$ 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).
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-87ER13671; FG0287ER13671
- OSTI ID:
- 1248473
- Alternate ID(s):
- OSTI ID: 1247608; OSTI ID: 1733332; OSTI ID: 1831802
- Journal Information:
- Journal of Chemical Physics, Vol. 144, Issue 14; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Full dimensional Franck-Condon factors for the acetylene $\tilde{A}$ 1 A u —$\tilde{X}$ 1Σ$^{+}_{g}$ transition. I. Method for calculating polyatomic linear—bent vibrational intensity factors and evaluation of calculated intensities for the gerade vibrational modes in acetylene
Polyad quantum numbers and multiple resonances in anharmonic vibrational studies of polyatomic molecules