A combined laser spectroscopic and theoretical study on the electronic structure of platinum monoxide (PtO)

Abstract

The laser-induced fluorescence (LIF) excitation spectra in the visible region of 16,800 – 23,800 cm^-1 and the dispersed fluorescence spectra of the gas-phase platinum monoxide (PtO) molecule have been investigated. Eight rotationally and isotopically resolved excitation bands are newly observed and assigned to the transitions from the ground X ³Σ^⁻₀₊ state to five excited electronic states. Two components of the ground state and an excited ¹Δ₂ state are distinguished in low-energy region. The rotational constants, band origins, and vibrational frequencies of all the observed states are obtained by rovibrational analysis. High-level ab initio calculations are performed on the Λ-S and Ω states below 30,000 cm^-1 and are used to identify the observed transitions. Notably, nine Ω = 0⁺ states are predicted by calculations, and their energy distributions are in agreement with the experimental results.