Polarization anisotropy effects for degenerate vibrational levels
© 2013 by Taylor & Francis Group, LLC. When molecular ions in the gas phase have high-enough symmetry to support degenerate vibrational states, one can expect the effect of solvation to be particularly apparent in as much as motions of the solvent as can be expected to lower the ion symmetry and remove these degeneracies. This perturbation may give rise to splittings of the degenerate vibrational states if the average symmetry is lowered in the solvent. But the splittings may only be transient while leaving the average structure with apparently degenerate states. These possibilities must be considered on an individual basis. In either case, it is not obvious what is the composition of the nearly degenerate normal modes of the molecule. The splitting or lack of splitting, and the properties of the resulting eigenmodes can provide direct information of the solvent shell structure and dynamics that may not be so distinctive in similar experiments on lower symmetry ions. Thus, this chapter focuses on what are the important parameters of the structural and hydration dynamics of highly symmetric molecular ions that pertain to their vibrational dynamics and structure. We describe the special properties of highly symmetric ions and how their interactions with water are seen by linear, vibrational pump-probe, and echo infrared (IR) methods applied to their degenerate modes.
Publication Source (Journal or Book title)
Ultrafast Infrared Vibrational Spectroscopy
Kuroda, D., & Hochstrasser, R. (2013). Polarization anisotropy effects for degenerate vibrational levels. Ultrafast Infrared Vibrational Spectroscopy, 169-202. https://doi.org/10.1201/b13972