Ab initio calculations of radiative transition probabilities in the X 1σ + state of SiO and the X 2σ +and A 2 Π states of SiO +

Abstract

Potential energy and dipole moment functions have been calculated for the X 1σ + state of SiO and for the X 2σ + and A 2 Π states of SiO + using MC SCF wavefunctions and large basis sets. For SiO the calculated dipole moment of 3.01 D is in good agreement wth the experimental value of 3.088 D. The dipole moments of the X and A states of SiO + are calculated to be 4.28 D and 2.89 D. respectively. For SiO + the transition moment function between the X and A states has also been evaluated, and rates for all important transitions within and between the X and A states are given (υ ⩽ 10): The SiO + ion is predicted to be an excellent IR emitter. It is found that all vibrational levels between 1 ⩽ υ ⩽ 10 of the X 2σ + state are almost entirely radiatively depopulated via transitions into energetically lower-lying vibrational levels of the A 2Π state. From the transition rates radiative lifetimes for the first ten vibrational levels of each state have be predicted. For the X state they lie between 70 μs and 423 ms and for the A state between 140 μs and 336 ms.