Knowledge Bank

Lanthanum oxide, LaO$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$, 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 LaO$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ 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.