			15min:

MASS-ANALYZED THRESHOLD IONIZATION OF LaO₂.

LU WU, CHANGHUA ZHANG, SERGIY KRASNOKUTSKI AND DONG-SHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.

Lanthanum oxide, LaO₂, is produced in a pulsed laser-vaporization metal-cluster source and studied by mass-analyzed threshold ionization (MATI) spectroscopy. From the MATI spectrum, the adiabatic ionization energy of LaO₂ is determined to be 40134 (5) cm^-¹ or 4.976 (6) eV, and La⁺-O stretching and O-La⁺-O bending frequencies are measured as 656 and 120 cm^-¹. The measured ionization energy is about 3.0 eV lower than the value predicted by recent high-level ab initio calculations. In this talk, we will discuss the discrepancy between the experiment and theory and the electronic transition observed in our experiment.