Vibrational levels near dissociation in Mg2 and long-range forces

Abstract

The vibrational levels v = 0 – 12 of the (ground state) van der Waals molecule, Mg₂, were observed and analyzed by Balfour and Douglas [Can. J. Phys. 48, 901 (1970)]. It was subsequently shown that the outer turning points of the higher observed levels were sensitive to the r⁻⁶ and r⁻⁸ terms of the long‐range potential. We have reexamined a plate of Mg₂ spectrum generously made available to us by Balfour and Douglas and obtained analyses of two bands involving v = 13. We have constructed new RKR potentials up to v = 13 for various values of J(14, 20, 32) which have turning points at distances as large as 8.28 Å. The analysis of these data to obtain more reliable values of the dissociation limit [D₀ = 404.1 (±0.5) cm⁻¹] and of the C₈ coefficient [C₈ = 0.51(±0.09) × 10⁸ cm⁻¹ Å⁸] is given.