MASS-SELECTED ANION-ZERO KINETIC-ENERGY PHOTOELECTRON-SPECTROSCOPY (ANION-ZEKE) - GROUND AND LOW EXCITED-STATES OF FEO

Photodetachment-photoelectron (PD-PES) and anion-zero kinetic energy p hotoelectron (anion-ZEKE) spectra of FeO have been measured. The vibra tional progression bands of the X (5) Delta(5)(FeO)<--X (5) Delta(7/2) (FeO-) transition in the PD-PES spectrum exhibit substructure which co uld not be resolved in earlier PD-PES spectra, A comparison with the h igh resolution anion-ZEKE spectrum clearly shows the existence of a se cond low energetic electronic state which could be the a (7) Sigma(+) Of neutral FeO proposed by several authors. In addition, for the A (5) Sigma state of FeO an excess energy of 4050cm(-1) was found. Vibrati onal frequencies for the X (5) Delta, a (7) Sigma(+), and A (5) Sigma( +) states have been determined as 881, 887, and 800 cm(-1). All spin o rbit splittings of the neutral and anionic ground states could be meas ured directly or deduced from spin orbit combination transitions. We s ucceeded in resolving the rotational envelops of the vibrational origi n of the neutral-anion ground states transition with indicated single rotational liner of the Delta J= + 3/2 branch. (C) 1997 American Insti tute of Physics,.