Absolute photoabsorption cross sections for the lowest excited state (4 2Γ of Kr2F and the ground state (1(1/2)u) of Kr2+ have been measured in the visible and ultraviolet (Kr2F: 248, 308, 335-600 nm; Kr2+ : 360-500 nm). As predicted by theory, the Kr2F spectrum is dominated by the 9 2Γ ← 4 2Γ band which peaks below 340 nm and correlates with the Kr2+ 2(1/2)g ← 1 (1/2)u transition. However, Kr2F(4 2Γ) and Kr2+ (1 (1/2)u) both absorb more strongly for wavelengths beyond ∼450 nm than expected, apparently owing to a nonthennalized Kr2+ vibrational distribution. Despite interference from Kr2F stimulated emission between ∼350 and 460 nm, the experimental results show the Kr2F(4 2Γ) and Kr2+ absorption profiles to be similar for λ≥460 nm but diverging rapidly as λ increases from 335 to 360 nm. At 360 nm, the absorption cross sections differ by a factor of 3. Contrary to theoretical expectations, the Kr2F absolute absorption cross section is consistently smaller (typically < 40%) than that for Kr 2+ which suggests that the impact of F- on the Kr2+ oscillator strengths is significant.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry