The laser induced fluorescence spectrum of jet‐cooled XeKr has been measured in the vicinity of the Xe 6s[3/2]01–1S0 atomic transition at 68 045.663 cm−1. The spectrum consists of two band systems, corresponding to transitions to the Ω=0+,1 electronic states from v″=0 of the ground electronic state. By using the observed band positions and intensities, we have constructed model potentials for both excited electronic states. The Ω=0+ state has a double minimum potential [inner well, re′ = 3.09(3) Å, De′ = 624(3) cm−1; outer well, re′ = 5.1(2) Å, De′ = 101(1) cm−1] while the Ω=1 state potential has only a shallow van der Waals potential [re′ = 5.24(4) Å, De′ = 52.2(7) cm−1]. The double minimum potential for the Ω=0+ state and the difference between the potentials for the Ω=0+ and Ω=1 states are understood in terms of the dominance of two different types of bonding interactions over different ranges of the internuclear distance. At long range, the interaction is dominated by weak dispersion and overlap repulsion between the closed shell Kr atom and the excited Xe atom, giving rise to shallow minima at r≊5 Å in both states. At short range, the XeKr interaction is better described by a XeKr+ ion‐core with an excited 6sσ Rydberg electron.
The Ω=0+ state is associated with the strongly bound 2Σ+1/2 XeKr+ ion‐core, while the Ω=1 state corresponds to the weakly bound 2Π3/2 XeKr+ ion‐core. The dual nature of the bonding which gives rise to the double minimum potential in the Ω=0+ state is similar to the bonding seen in excited states of HgAr and HgNe [Duval et al., J. Chem. Phys. 85, 6324 (1986); Okunishi et al., ibid. 98, 2675 (1993); Onda et al., ibid. 101, 7290 (1994); Onda and Yamanouchi, ibid. (submitted)] or the long range s–s, short range d–d bonding seen in the ground state of Cr2 [Casey and Leopold, J. Chem. Phys. 97, 816 (1993)], but is different from some double minima states seen in other diatomics, such as H2 (E,F 1Σ+g) [Davidson, J. Chem. Phys. 35, 1189 (1960); Kolos and Wolniewicz, ibid. 50, 3228 (1968)], Na2 (4 1Σ+g) [Tsai et al., J. Chem. Phys. 101, 25 (1994)], and Cl2 (1 1Σ+u) [Yamanouchi et al., Chem. Phys. Lett. 156, 301 (1989); Tsuchizawa et al., J. Chem. Phys. 93, 111 (1990)] which arise from curve crossings between ionic and covalent diabatic states. © 1994 American Institute of Physics.