Electronic Transitions Of Scandium Monoxide

Abstract

The electronic transition spectrum of scandium monoxide (ScO) in the spectral region between 290 and 311 nm has been recorded using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The ScO molecule was produced by reacting laser-ablated yttrium atoms with O$_{2}$ gas seeded in argon. Twenty transition bands were observed and thirteen of them have been selected for further studied by optical-optical double resonance (OODR) spectroscopy. Higher-lying electronic excited states have been reached via the intermediate B$^{2} \Sigma^{+}$ state from the ground X$^{2} \Sigma^{+}$ state. Our analysis indicates that the upper states conform to Hund’s case (c) coupling scheme, the sub-states analyzed so far have $\Omega$ = 0.5 and 1.5. In addition, for the first time, a quartet state namely $^{4} \Sigma^{+}$ state has been identified experimentally. Least squares fits of the measured rotational lines yield molecular constants for the newly identified excited states.