Absorption spectrum of the Mg₂ molecule

Abstract

The absorption spectrum of the Mg2 molecule, which occurs in a furnace containing Mg vapor, has been photographed with a high resolution spectrograph. The rotational structures of the bands have been analyzed and the rotational and vibrational constants of the two states determined. The bands are found to arise from a 1Σ–1Σ transition between a very lightly bonded ground state and a more stable excited state. The R.K.R. potential energy curve of the ground state, which has a dissociation energy of 399 cm−1, has been determined. The more important constants of the ground state are ωe = 51.12 cm−1, ωexe = 1.64 cm−1, re = 3.890 Å and those of the upper state are ωe = 190.61 cm−1, ωexe = 1.14 cm−1, re = 3.082 Å.

Scattering length of the ground-stateMg+Mgcollision

“…We will show lateron by solving the Schrödinger equation for the RKR and IPA potentials that the IPA potential reproduces the term values significantly better than the RKR potential of Ref. [17]. For the IPA potential we take the dissociation energy D e to be 431.0(1.0) cm −1 in accordance with fit of Ref.…”

“…[17] and the IPA potential constructed in this work from data published in Ref. [18] are shown in Fig.…”

“…In this paper we present our calculation of the ground state Mg 2 scattering length and cross-section as a function of the collision energy, using a potential constructed from high resolution spectra of the magnesium dimer measured by Balfour and Douglas [17]. At temperatures below 5 mK ground state Mg collisions are in the s-wave scattering regime and the l = 0 phase shift determines the cross-section and, at zero collision energy, the scattering length.…”

“…Firstly, a Rydberg-Klein-Rees (RKR) potential curve has been constructed in Ref. [17] from their measurement of the rovibrational levels (ν = 0 -12, J = 10 -76) of ground state Mg 2 . Secondly, Vidal and Scheingraber [18] have reevaluated the molecular constants of Ref.…”

“…Secondly, Vidal and Scheingraber [18] have reevaluated the molecular constants of Ref. [17] and improved upon the RKR analyses by applying a variational procedure based on the inverted perturbation approach (IPA). Finally, there exist a large number of theoretical electronic structure calculations [19][20][21][22][23][24][25][26][27][28][29][30] of the ground state Mg 2 potential.…”