SOLVING THE PUZZLE OF TETRATOMIC, 23-VALENCE-ELECTRON MOLECULES

Author Institution: Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441Because of extensive electron correlation, the ground-state structures, infrared spectra, and chemical bonding properties of a number of tetratomic molecules which possess 23 valence electrons are anomalous. Approaches which have recently been helpful in understanding this phenomenon include {\ital{ab initio}} calculations and spectroscopic observations of these species trapped in solid neon at temperatures near 4 K. Molecules for which infrared spectra have been obtained and which will be discussed include NO$_3$, NNO${_2}$ anion, BF${_3}$ cation, and O${_4}$ cation