Evidence of a weak dipole transition moment between the X0g+1 and 31u(53P1) electronic energy states in Cd2

Theoretical and experimental evidence of a weak Mz(R) dipole transition moment between the X0g+1 ground and 31u(53P1) excited states in Cd2 is presented. Two independent attempts at recording an excitation spectrum of the 1u3←X0g+1 transition using a laser beam crossed with a supersonic free-jet expansion beam are reported. The measurements were performed in a spectral range predicted as a result of both ab initio calculations of the electronic energy-state potentials involved in the transition and a simulation of the excitation spectrum. Unfortunately it was impossible to provide unambiguous experimental support for the calculated 31u-state potential, due to the very poor signal to noise ratio. However, the experimental results corroborate the very small values of the 〈1u3|Mz|X0g+1〉 elements obtained in the calculations. This work provides as a reliable starting point for further analysis of the 31u-state characteristics.