Long-range Interactions for the A$\text{}^{3}$1$\text{}_{u}$ and B$\text{}^{3}$0$\text{}_{u}^{+}$ States of Cd$\text{}_{2}$ from Line Shape Measurements

We report on very precise measurements of the absorption profile of the 326.1 nm resonance line of cadmium broadened by interactions with the ground state Cd atoms under thermal equilibrium. The experimental red wing profiles, corrected for the Boltzmann factor at different temperatures, are analysed in terms of the long-range potential parameters including dispersion and resonant interactions. The resonant interaction energy constant C$\text{}_{3}$ is calculated to be 2.31×10$\text{}^{-2}$ eV Å$\text{}^{3}$ and the van der Waals constant C$\text{}_{6}$ for difference potentials between the ground state X$\text{}^{1}$0$\text{}_{ }^{+}$g and the excited states B$\text{}^{3}$0$\text{}_{u}^{+}$ and A$\text{}^{3}$1$\text{}_{u}$ of Cd$\text{}_{2}$ derived experimentally are found to be (182.6± 8) eV Å$\text{}^{6}$ and (289±4) eV Å$\text{}^{6}$, respectively. The former is determined for the first time and the latter is considerably corrected in comparison to earlier determination. The van der Waals constant C$\text{}_{6}$ for the ground state of Cd$\text{}_{2}$ is discussed and estimated to be C$\text{}_{6}^{g}$=(247± 40) eV Å$\text{}^{6}$.