Knowledge Bank

Interatomic potential parameters for the ground $X1,2 2\pi 1/2,3/2$ and excited $B \mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma 1/2$ states of jet-cooled van der Waals complexes of Al and In atoms with rare gases have been determined from fluorescence excitation and emission spectra. Vibrational numbering in the B states is established from isotopic and rotational broadening of fluorescence excitation lineshapes. Bond diatances are estimated by comparison with analogous states of alkali-rare gas molecules, and by modelling observed relative emission intensities with calculated Franck-Condon factors. Horse potentials are found to adequately describe the data for the ground states, but for the excited states there are indications of departures from Morse functions at large internuclear distances. Multiplet splittings in Al-and In-rare, gas complexes are discussed in terms of an empirical treatment of spin-orbit coupling.