$B\,^1\Sigma^{+}_{u}$ and $EF\,^{1}\Sigma^{+}_{g}$ level energies of D$_{2}$

TL;DR

This study provides highly accurate absolute energy levels for specific rovibrational states of molecular deuterium (D₂), combining laser spectroscopy and Fourier-transform spectroscopy to improve precision and expand existing data.

Contribution

The paper presents the first combined high-precision measurements of D₂ energy levels across multiple states, significantly reducing uncertainties and providing comprehensive data for future spectroscopic applications.

Findings

Level energies of B and EF states determined with uncertainties as low as 0.0005 cm$^{-1}$.

Accurate energies for rovibrational levels up to v=8, N=10 for B state.

Tabulated wavelengths of D₂ Lyman transitions for future research.

Abstract

Accurate absolute level energies of the $B\,^1\Sigma^{+}_{u}$, $v=0-8, N$ and $EF\,^{1}\Sigma^{+}_{g}$, $v=0-21, N$ rovibrational quantum states of molecular deuterium are derived by combining results from a Doppler-free two-photon laser excitation study on several lines in the $EF\,{}^{1}\Sigma_{g}^{+}-X\,{}^{1}\Sigma_{g}^{+}$ (0,0) band, with results from a Fourier-transform spectroscopic emission study on a low-pressure hydrogen discharge. Level energy uncertainties as low as 0.0005 cm$^{-1}$ are obtained for some low-lying $E\,^{1}\Sigma^{+}_{g}$ inner-well rovibrational levels, while uncertainties for higher-lying rovibrational levels and those of the $F\,^{1}\Sigma^{+}_{g}$ outer-well states are nominally 0.005 cm$^{-1}$. Level energies of $B\,^1\Sigma^{+}_{u}$ rovibrational levels, for $v \leq 8$ and $N \leq 10$ are determined at an accuracy of 0.001 cm$^{-1}$. Computed wavelengths of D$_2$ Lyman transitions in the $B\,^1\Sigma^{+}_{u}-X\,^{1}\Sigma^{+}_{g}$ ($v,0$) bands are also tabulated for future applications.