Multireference-CI calculations of radiative transition probabilities in C−2

Electronic transition moment functions for the dipole allowed transitions among the X 2∑+g, A 2Πu, and B 2∑+u states of C−2 have been calculated from highly correlated MCSCF-SCEP wave functions. Vibrational band transition probabilities for all bound–bound transitions have been evaluated, and radiative lifetimes of bound vibrational levels are obtained. For the B 2∑+u, v′=0 state, the calculated lifetime of 76.5 ns is in excellent agreement with recent experimental values. Strong emission from the A 2Πu state in the infrared spectral region is predicted.