Vacuum ultraviolet laser spectroscopy. IV. Spectra of Kr2 and constants of the ground and excited states

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Abstract
Krypton dimers formed by supersonic jet expansion have been excited with tunable, and monochromatic VUV radiation leading to isotopically resolved fluorescence excitation spectra of three band systems at 125, 124, and 117 nm. Unambiguous upper-state vibrational numbering was possible, resulting in evaluation of the spectroscopic constants for the three lowest excited states. From system I at ∼125 nm, with bands v′=32 to 38 and v″=0, constants for the A 3Σ+u state of Kr2 were found to be T′e =74 303.9(8.0), ωe =244.60(43), ωex′e =2.6045(60), and De=5807.0(8.0) cm−1. Band system II at ∼124 nm, with bands v′=30 to 38 and v″=0, led to constants for the B 1Σ+u state, T′e =75 426.8(1.7), ωe =219.50(10), ωex′e =2.2325(15), and De =5629.1(2.5) cm−1. Improved values for constants of the C 1Σ+u state were obtained from analysis of band system III at ∼117 nm (with bands v′=0 to 5, and v″=0 to 2): T′e =85 520.60(10), ωe =43.82 (10), ωex′e =1.812(18), and De =465.3(2.0) cm−1. Vibrational constants for the ground state were obtained from bands with v″=0, 1, 2, namely ω″e =23.53(2) cm−1 and ωex″e =1.07(1) cm−1. Analyses of resolved rovibronic structure for all three band systems yielded values of rotational constants for the ground and three excited states, with the equilibrium internuclear distance r″e =4.017(12) Å for 84Kr2. These new data were used to derive potential energy curves.