Gerade/ungerade symmetry-breaking in HD at the <i><b>n</b></i> = <b>2</b> dissociation limit

Abstract

Abstract:We report on a study of the I 1 g outer well state of HD. Via a resonance-enhanced XUV + IR (extreme ultraviolet + infrared) excitation scheme, rovibronic levels (v = 0-2, J = 1-4) are populated and probed by pulsed lasers. Level energies are measured with an accuracy of ≈0.03 cm −1 . Due to gerade-ungerade symmetry breaking, the long-range behavior of the I potential in HD deviates from that of H 2 and D 2 . When this deviation is taken into account a semi-empirical potential for the I [Traduit par la rédaction]

Gerade-ungerade symmetry breaking in HD: Bound states supported by the I′Πg1 outer potential well

“…2. 2 As in the case of the f-parity states, the best agreement with the experiment is obtained from coupled-state calculations using the ab initio data for IIЈ 1 ⌸ g potential from Ref. The differences of the two sets of eigenenergies, corresponding to two different ab initio sets of data for the IIЈ 1 ⌸ g potentials, follow the same pattern as in the case of f-parity states.…”

“…In their construction of the semiempirical potential De Lange et al 2 used for the matrix element Eq. ͑3.5͒ is the leading term in the expansion of this difference in terms of inverse powers of nuclear masses.…”

“…One can see that the differences between the two sets of levels, corresponding to ab initio data from Refs. 2 This potential was constructed by using for R Ͻ 12 the ab initio data for the IIЈ 1 ⌸ g potential from Ref. The results for the probabilities for finding the particular electronic state in an eigenstate ͑͗ 1 ͉ 1 ͘ and ͗ 2 ͉ 2 ͒͘ are, however, practically the same in both sets.…”

Theoretical calculations of excited rovibrational levels of HD. Term values and transition probabilities of VUV electronic bands

“…There have been few spectroscopic studies of this molecule since the VUV absorption analysis of HD by Dabrowski & Herzberg (1976) that followed the study by Monfils (1965). Ubachs and colleagues (de Lange et al 2000;Hinnen et al 1995;Reinhold et al 1999) have performed specific experimental studies at very short wavelengths and discussed the nonadiabatic coupling effects in the Rydberg excited electronic levels of HD. Symmetry-breaking effects between u and g electronic excited levels have been inferred from these experiments.…”

Gerade–ungerade symmetry breaking in bound states localized in the II′ 1Πg outer potential well of HD

“…This state is strongly coupled to the C 1 g state at distances beyond the outer minimum. Recently, very precise and systematic measurements of the rovibrational states associated with the outer minimum have been carried [4,5] and in order to interpret their results these authors have constructed a semi-empirical potential, which attempts to incorporate the effect of g-u coupling. But since the g-u coupling does not vanish asymptotically, the notion of a unique potential is not compatible with two distinct dissociation limits.…”