Theoretical study on the transition properties of AlF

Abstract

Potential energy curves of the X1Σ+ and A1Π states of the AlF molecule are studied through the combination of the multi-reference configuration interaction (MRCI) approach and Davidson corrections (MRCI+Q). The AWCV5Z basis set is employed in the calculations. The transition dipole moments (TDMs) of the A1Π ↔ X1Σ+ transition are explored based on the AWCV5Z basis set and (4, 2, 2, 0) active space. The Schrödinger equation is solved via the LEVEL 8.2 program, and the vibrational levels and rotational constants of the X1Σ+ and A1Π states are calculated. It is shown that the AlF molecule has high diagonal Franck–Condon factors (f 00 = 0.9949 and f 11 = 0.9854) and large Einstein coefficients for the transition of A1Π (ν′ = 0) ↔ X1Σ+ (ν″ = 0). In addition, the radiative lifetimes of the vibrational levels are close to 10−9 s for the A1Π state. The line intensities of the A1Σ (ν′ = 4 – 15) ↔ X1Σ+ (ν″ = 0) transitions are also calculated. The calculated TDMs and transition probabilities in this work are credible and provide some guidance for the study of similar transitions, particularly for exploring interstellar space.