The emission band system of GeF4 +

A discrete electronic emission spectrum around 400 nm is observed at a low rotational temperature following electron impact ionization of a molecular beam of GeF4. The narrow rotational envelope of the bands confirms that the emitter is the parent molecular ion of GeF4. By comparison with a recent study of fast ion beam excitation of GeF4 and with photoelectron data, the spectrum is assigned to GeF4 + . The spin-orbit splitting constant of  has a small negative value, and this state exhibits Jahn-Teller distortion from tetrahedral symmetry with both v 4 (t 2) and v 2 (e) being Jahn-Teller active vibrations. The results are compared with those from the analogous  spectra of CF4 + and SiF4 +.