Rotational structure of the band of the transition in 228Cd2: Direct determination of the ground- and excited-state bond lengths

Analysis of a first-time recorded rotational structure of the υ ′ = 45 ← υ ″ = 0 band of the 1 0 u + ( 5 1 P 1 ) ← X 1 0 g + transition in 228Cd2 is presented. In the interpretation, an influence of a nuclear spin intensity alternation and rotational levels symmetry properties are taken into account. From the analysis, the B υ ″ = 0 = 0.0206 ± 0.0005 cm - 1 and B υ ′ = 45 = 0.0277 ± 0.0005 cm−1 rotational constants, and the R e ″ = 3.77 ± 0.04 Å and R e ′ = 2.94 ± 0.03 Å bond lengths are determined for the 114Cd114Cd. The obtained value of R e ″ is close to that obtained with an assumption of a covalent admixture to the dominant van der Waals bonding of Cd2 and is smaller than that derived with an assumption of pure dispersion forces.