KXe excimer absorption and S → D, S → F collision induced satellites in K–Xe mixtures

The ultraviolet and visible absorption spectra of potassium vapor–xenon mixtures have been studied for [K] and [Xe] as large as 7×1017 and 4×1019 cm−3, respectively. Collision-induced absorption is observed in the ultraviolet (285≤λ≲370 nm) for the 4s → nf, nd (4≤n≤8) transitions but peak absorption lies an average of ∼0.6 nm to the red side of the position of the electric dipole forbidden line. The 4s → 4f, 5f transitions, in particular, are quite strong, having peak reduced absorption coefficients measured to be 1.1×10−39 and 2.6×10−40 cm5, respectively. Also, the KXe (C 2Σ) excimer has been observed in absorption for the first time. Absorption at the band peak (reduced absorption coefficient of ∼2×10−40 cm5 at λ=507 nm) is roughly two orders of magnitude weaker than that for the analogous bands of CsXe and RbXe and is displaced at least 5 nm to the blue side of the peak (∼520 nm) in the emission spectrum. Six reproducible undulations to the blue side of the absorption maximum display a periodicity of 111±17 cm−1.