Rydberg series of Ar2 and Kr2 have been observed in the visible and ultraviolet (350≤Aλ560 nm) absorption spectra of the lowest-lying metastable states of the dimer (ns 3∑ u+ (1u, 0u-); Ar: n = 4, Kr: n = 5). The most prominent series for Ar2 and Kr2 are assigned to ns 3∑u+ → mp 3Πg (Ar: 5≤m≤15; Kr: 6≤m≤16) Rydberg transitions of the diatomic molecule and adiabatic ionization potentials are determined from an extrapolation of the series to their limits (m → ∞) to be 116 356 ± 340 cm-1 (14.43 ± 0.04 eV) for Ar2 and 104 616 ± 150 cm-1 (12.97 ± 0.02 eV) for Kr2. The dissociation energies of the A 2∑u+ [1 (1/2)u] dimer ion states of Ar2 and Kr2 are, therefore, 1.33 ± 0.04 and 1.03 ± 0.02 eV, respectively. All of the observed Rydberg states have an A 2∑u+ ion core. Binding energies of the lowest observed 3Πg states, were determined to be (1.331 ± 0.005) eV for Ar2 and (1.030 ± 0.001) eV for Kr2. The quantum defects for the Ar 2 and Kr2 series ( 1.656 ± 0.006 and 2.621 ± 0.004, respectively) and ωe - 2ωex e for the ns 3∑u+ metastable state of Ar2 (303 ± 20 cm-1) and Kr2 (172 ± 10 cm-1) were also measured and the vibrational frequencies are consistent with previously reported values. Absorption peaks which are attributed to ns 3∑u+ → m′p 3∑g+ Rydberg transitions of Ar2 (6≤m′≤10) and Kr2 (7≤m′≤10) are also reported.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry