Xe₂Cl and Kr₂F excited state (4 ²Γ) absorption spectra: measurements of absolute cross sections

Absolute absorption cross sections for the lowest excited states (4 ²Γ) of Xe₂Cl and Kr₂F have been measured at discrete wavelengths in the visible and ultraviolet (Xe₂Cl: 325 ≤ λ ≤ 495 nm; Kr₂F: 248 ≤ λ ≤ 570 nm). The wavelengths observed for the 9 ²Γ ← 4 ²Γ band peak in each spectrum confirm the predictions of theory. However, the spectral profile and magnitude of the Xe₂Cl and Kr₂F absorption cross sections are considerably different from those predicted theoretically for the corresponding rare gas dimer ions, Xe⁺₂ and Kr⁺₂.