Vibronic Interaction in Molecules and Ions. I. The first order Jahn-Teller interaction in doubly degenerate electronic states of C3ν type molecules

Abstract

Expressions relevant to optical and electron spectroscopy are presented for calculation of the vibronic energy levels and Franck-Condon factors due to excitation of a Jahn-Teller active e vibrational mode in an electronic E state of C3v type molecules. Both A → E and E → A electronic transitions are investigated with allowance of different vibrational energies in the initial and final states. Energy levels and Franck-Condon factors including consideration of hot band transitions are explicitly given for some selected cases. Application is made to the fourth electron band at 18 eV of the electron spectrum of SO3. The vibronic band structure is well reproduced when the Jahn-Teller coupling parameters D3 and D4 of the ν3 and ν4 active modes are 0.06 and 0.35, respectively. A theoretical estimation is also made of the Jahn-Teller stabilization energy of SO3+. Finally, the X → B Rydberg transition of CF3I is discussed and a value of 0.01 is suggested for the Jahn-Teller coupling parameter D6.