Computer simulation of the rotational structure of vibronic bands of CF+4and SiF+4[Dtilde]2A1-[Ctilde]2T2

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Abstract
A computer simulation of the rotational structure of vibronic bands of the recently discovered emission spectra in CF+ 4 and SiF+ 4 [Dtilde] 2 A 1-[Ctilde] 2 T 2 (Molec. Phys., 60, 761, 771) is presented. The model allows for Coriolis splitting, spinorbit splitting and Jahn-Teller distortion in the [Ctilde] 2 T 2 state, and can be applied to [Dtilde]-[Ctilde] vibronic bands of either ion which do not involve the Jahn-Teller active vibrations. In CF+ 4 [Ctilde] there is no Jahn-Teller distortion, and a simulation of the 10 2 band at 381 nm compares excellently with the experimental spectrum obtained at a low rotational temperature. Estimates of the two rotational constants are made from the [Ctilde] and [Dtilde] state photoelectron bands of CF4, and the simulation then gives values for the Coriolis and spin-orbit splitting in CF+ 4 [Ctilde] 2 T 2. In SiF+ 4 a simulation can only be made of the 00 0 band at 551 nm because both v 2 and v 4 vibrations in [Ctilde] 2 T 2 are Jahn-Teller active; the distortion is shown to be dynamic in nature. The simulation is not so satisfactory because estimates for the rotational constants are less accurate than in CF+ 4 and the Jahn-Teller effect in [Ctilde] 2 T 2 means that more constants are needed to determine the rotational structure. The spin-orbit splitting in the [Ctilde] 2 T 2 state of both ions is small and positive, and the Coriolis constant in CF+ 4 has a value substantially reduced from its limiting value of + 1. The results are interpreted in terms of the molecular orbital diagram for CF4 and SiF4.