Spectroscopic Properties and Spin-Orbit Coupling of Electronic Excited States of GeCl .

The electronic structure and spectroscopic properties of GeCl + are studied by high-level ab initio calculations by considering spin-orbit coupling (SOC). The potential energy curves (PECs) and spectroscopic constants of 12 Λ-S states and 23 Ω states are calculated using the multi-reference configuration interaction plus Davidson correction method (MRCI + Q ), which are in good agreement with the experiment. Based on the calculated SO matrix and the PECs of the Ω states, the interaction between the d 3 Π state and other states caused by the SOC and the double-potential well structure caused by the avoided crossing rule and the properties of transitions d 3 Π 0+ -X 1 Σ + 0+ , d 3 Π 1 -X 1 Σ + 0+ , and a 3 Σ + 1 -X 1 Σ + 0+ are studied. Our results indicate that the previously observed spectra of GeCl + in the 290-325 nm range should be assigned as the a 3 Σ + 1 -X 1 Σ + 0+ transition. Moreover, the predissociation behavior of the d 3 Π state between the vibrational levels v ' = 1 and v ' = 10 is discussed, and the radiative lifetimes of transitions d 3 Π 0+ -X 1 Σ + 0+ and d 3 Π 1 -X 1 Σ + 0+ are evaluated on the order of microseconds, while a 3 Σ + 1 -X 1 Σ + 0+ is on the order of milliseconds. We estimate that the strongest bands of a 3 Σ + 1 -X 1 Σ + 0+ are the 0-16, 0-17, and 0-18 bands. This study will promote our understanding of the detailed electronic structure and spectra of the GeCl + radical cation.