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 (C²σ) 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±17cm^-1.