DECAY OF FESHBACH RESONANCES IN NO .2. DYNAMIC COUPLING TO RYDBERG STATES

For pt.I see ibid., vol.12, no.17, p.2925, 1979. The decay of four Feshbach resonance series into the A2 Sigma +, C2 Pi and D2 Sigma + Rydberg states and B2 Pi valence state has been observed by means of an electron impact spectrometer. New phenomena have been detected analogous to those occurring in autoionisation and imply the breakdown of the Born-Oppenheimer approximation. A vibrational propensity rule is observed for certain transitions which is accounted for by dynamic coupling between nuclear and electron motion.