Infrared laser spectroscopy of the a 3Σ+g–c 3Πu system of H2 and D2

Abstract

Doppler limited infrared laser spectra of H2 and D2 have been recorded in an ac discharge with diode laser sources and assigned to Δv=0 and ±1 sequence bands of the a–c system. Intense absorption signals from atomic hydrogen were also detected and used to confirm that some molecular spectra occurred in stimulated emission; as was found for a known D2 laser transition. Several of the diode spectra recorded at shorter wavelengths (Δv=1 sequences) cover regions previously observed by FTIR emission experiments on the a–c system. Both fine and hyperfine structure are revealed by the present studies and a preliminary analysis shows that while the a 3Σ+g state has negligible fine structure (at this resolution), hyperfine effects are apparent and are modeled using a bβS coupling case.

Optimal values of rovibronic energy levels for triplet electronic states of molecular deuterium

“…Taking into account random character of the differences we decided to consider the data of those papers as the results of independent experiments. Thus, the initial data set used for the start of the statistical analysis contains: 350 wavenumbers from paper [32] [28], and 3 from [29]. It should be stressed that the wavenumbers of spectral lines used in the present work are spread over the very wide range 0.896-28166.84 cm −1 from radio frequencies up to the ultraviolet.…”

“…All available values of rovibronic transition wavenumbers studied in emission, absorption, laser and anticrossing spectroscopic experiments of various authors [16,28,29,31,32,33,34,35] were analyzed in the present work. In overwhelming majority of the works the fine and hyperfine structures of lines have not been resolved, and the reported experimental wavenumbers correspond to intensity maxima of the observable line profiles.…”

“…Also 1 wavenumber from [35] and 3 wavenumbers from [29] were used in further analysis as two separate samples (18-th and 19-th) with RMS errors reported in original papers, because the errors were unchanged during the analysis.…”

“…In overwhelming majority of the works the fine and hyperfine structures of lines have not been resolved, and the reported experimental wavenumbers correspond to intensity maxima of the observable line profiles. In cases of partly resolved structure of lines [28,29] we used wavenumbers of the brightest components.…”

“…On our opinion the reported in [16] uncertainty σ = 0.05 cm −1 for all levels and all wavenumbers of lines is the overestimation caused by the randomization of various deviations when working with many thousands of levels and lines. It should also be mentioned that after publication of [16], new experimental data on the wavenumbers appeared [28,29].…”