Rotation and internal rotation in the vinyl cation C 2H 3+

Abstract

In the vinyl cation C 2H 3 + it is believed that there is a low barrier hindering the rotation of the three protons around the CC core, with the molecule remaining planar during this internal rotation. In this paper the semirigid bender formalism is adapted to calculate the rotation and internal-rotation energy levels of this species. Numerical results are presented for a variety of different hindering potentials. The symmetries of the levels, the nuclear spin statistical weights, and the selection rules for allowed electric dipole transitions are all determined.