Long-range potentials for the<i>X</i>¹Σ⁺and<i>a</i>³Σ⁺states of the NaK molecule

Abstract

Abstract Fluorescence spectra of the NaK molecule excited by the 4765 Å and 4880 Å lines of an argon-ion laser have been recorded at high resolution by Fourier-transform spectrometry. Constants for the ground state X 1Σ+ and for the first excited state, a 3Σ+, have been determined from a simultaneous least-squares fit to a total of 1758 lines assigned to five systems. Rotationless potentials for these two states have been calculated at internuclear distances out to about 9·3 Å for the ground state and to about 9·1 Å for the triplet state. The dissociation energy, D e (NaK), is found to be 5274·9 ± 0·5 cm-1, and the long-range potential for X 1Σ+ is given by with V in cm-1, r in Å. Values of the potential constants are in satisfactory agreement with the results of recent calculations.