Ground-State Reversal by Matrix Interaction: Electronic States and Vibrational Frequencies of CUO in Solid Argon and Neon

Abstract

A 3Φ state is found for the CUO molecule (made by reaction of laser-ablated U and CO) trapped in solid argon, in contrast to the 1Σ+ ground state in solid neon. The new electronic state results from the transfer of an electron from a U−C bonding orbital to a nonbonding 5f orbital of the U atom, thus decreasing the U−C stretching frequency significantly. Infrared spectroscopy and relativistic DFT calculations have been used to characterize these two low-lying states of CUO.