Dissociation energies of the hydrogen and deuterium molecules

Abstract

Fluorescence-excitation spectroscopy near -84 nm has been used to measure the threshold for the dissociation of H~{B' 'X"+ ) =H{1s)+H(2s) at 118377.06+0.04 cm ' and the corresponding limit for D2 at 119029.72+0.04 cm '. The onset of dissociation was observed clearly, free from overlapping molecular lines, by the use of delayed quenching of 2s atoms produced by the photoexcitation pulse. These measurements have yielded the values Do(H2)=36118. 11+0. 08 cm ' and Do(D2)=36748. 38+0.07 cm ' for the dissociation energies of the ground electronic states X 'Xg+, in agreement with the latest ab initio calculations, which include nonadiabatic, relativistic, and radiative corrections. From the present values and recently determined ionization energies of H& and D&, the dissociation energies of the respective ions were found to be Do(H2+)=21379. 37+0.08 cm ' and Do(D2+)=21711.64+0.07 cm ', also in agreement with recent ab initio calculations.PACS number(s): 35.20.6s, 33.20.Ni, 32.50.+d

Observation of the I′ 1Πg outer well state in H2 and D2

“…8 the threshold region is overlapped by the wing of a strongly saturationbroadened resonance, we can derive an approximate value of 118377.2Ϯ0.1 cm Ϫ1 for the 1sϩ2s dissociation energy in the singlet gerade case, 0.14 cm Ϫ1 higher than the most accurate value found in the singlet ungerade system. 1,19 Further studies are needed to investigate the complex system of different dissociation limits that arise from the fine and hyperfine splitting of the nϭ1 and nϭ2 states of the hydrogen atom.…”

“…18 Direct XUV excitation of the dissociation continuum of electronic ungerade states and detection of the fluorescence of the products by Balakrishnan et al resulted an accurate determination of the dissociation energy of the hydrogen molecule. 1,19 Tsukiyama and co-workers observed a number of singlet gerade levels close to the (nϭ2) limit using resonanceenhanced two-photon transitions, excited by XUV and visible pulsed lasers and detected by observation of their fluorescence in the visible and near infrared. 2,16,20 Lifetimes were deduced from the exponential decay of the fluorescence.…”

Evidence for D2 dissociative chemisorption and electron affinity changes of bare and ion beam damaged polycrystalline diamond surfaces

“…We suggest that this mode originates from surface termination by residual hydrogen molecules mainly constituting UHV ambient, albeit, intensity of C-H mode exceeds that of C-D mode in spectrum (b). At present experimental conditions basic hydrogen pressure nearly three orders of magnitude lower than this of deuterium, however, because of the lighter isotopic mass hydrogen surface diffusion expected to be faster and its dissociation energy, D 0 , is lower (D 0 (H 2 )=36,118 cm -1 vs. D 0 (D 2 )=36,748 cm -1 ,[20]) than those of deuterium molecules. This small difference in dissociation energy can largely affect the activation energy, sticking probability and kinetics of the activated chemisorption process.Fig.…”

Quantum effects of nuclear motion in three-particle diatomic ions

“…Muonic systems were compared to data in the papers of Frolov [18,20,33,34]. c [35] d [36,37] e [36,38] f [39] The center of mass c is the barycenter of the three masses and it will have a position vector relative to either particle a 1 or a 2 given by…”