Fourier spectrometry investigation of the 1 3Σg+ →a 3Σu+ transition of the 7Li2 molecule

The High-Lying Vibrational Levels and Dissociation Energy of the a3Σ+u State of 7Li2

“…Assignment of the main and relaxation lines was straight- forward, and for v Љ ϭ 0 -6, the vibrational spacings at each value of N were compared with those obtained from our analysis of the 1 3 ⌺ g ϩ -a 3 ⌺ u ϩ transition (3,4) and the results generally agreed to within 0.005 cm Ϫ1 . Although the only new data obtained from the present experiments are the energies of the vЉ ϭ 7, 8, and 9 levels relative to the other vibrational levels, these levels are critical in examining the long-range behavior and in establishing a potential curve that is reliable up to the dissociation limit.…”

“…The sign of the scattering length, which can be deduced from the wavefunction of the last bound vibrational level, determines the stability of the Bose-Einstein condensate. Martin et al (3) and Linton et al (4) analyzed extensive spectra of the 1 3 ⌺ g ϩ -a 3 ⌺ u ϩ transition in 7 Li 2 and 6 Li 2 , respectively, at high resolution using a Fourier transform spectrometer and were able to determine accurate vibrational and rotational constants for the a state and a dissociation energy of 333 Ϯ 1 cm Ϫ1 . The first observation of the a 3 ⌺ u ϩ state was by Xie and Field (2) using perturbation-facilitated optical-optical double resonance (PFOODR) on the 6 Li 2 isotopomer.…”

“…In a theoretical investigation of the scattering length of 7 Li, Moerdijk et al (6) calculated an IPA potential curve for the a 3 ⌺ u ϩ state in which they combined the results of our previous experiments (3,4) with the data being presented here. One of the predictions from their potential is that the last bound level in 7 Li 2 is v ϭ 10, N ϭ 3 and that the v ϭ 10, N ϭ 0 level is bound by 11.4 GHz.…”

The potential energy surface for spin-aligned Li3(1 4A′) and the potential energy curve for spin-aligned Li2(a 3Σu+)

“…Semiempirical potentials for this triplet state have been improved steadily in recent years. An analysis of the experimental energy levels was performed in 1988 by Martin et al 12 who obtained Rydberg-Klein-Rees ͑RKR͒ classical turning points for the lowest eight states (0рр7) of 7 Li 2 by analyzing spectroscopic data. These were then combined with 6 Li 2 data to obtain self-consistent curves for both isotopes.…”

“…11 For lithium, the lightest of the alkalis, most of the work done has been devoted to understanding the properties of the low energy elastic scattering of two Li atoms and other features of the a 3 ⌺ u ϩ state of the lithium dimer 7 Li 2 . [12][13][14][15][16][17][18][19] To the best of our knowledge the present work is the first effort to deal with the full potential of the spin-aligned lithium trimer, but another group is currently working on it. 20 Because the interaction between two spin-aligned alkali atoms is basically a nonbonding van der Waals interaction, one might think that the interaction between three such spinaligned atoms would be mostly due to pairwise additive twobody interactions with little contribution from three-body effects.…”