Fourier transform spectroscopy of HD in the Extreme Ultraviolet at $\lambda= 87-112$ nm
Résumé
Absorption spectroscopy in the vacuum ultraviolet (VUV) domain was performed on the hydrogen-deuteride molecule with a novel Fourier-Transform spectrometer based upon wavefront division interferometry. This unique instrument, which is a permanent endstation of the undulator-based beamline DESIRS on the synchrotron SOLEIL facility, opens the way to Fourier-Transform spectroscopy in the VUV range. The HD spectral lines in the Lyman and Werner bands were recorded in the 87-112~nm range from a quasi-static gas sample in a windowless configuration and with a Doppler-limited resolution. Line positions of some 268 transitions in the $B^1\Sigma^+_u\,(v'=0-30) \leftarrow X^1\Sigma^+_g\,(v''=0)$ Lyman bands and 141 transitions in the $C^1\Pi_u(v'=0-10) \leftarrow X^1\Sigma^+_g(v''=0)$ Werner bands were deduced with uncertainties of 0.04$\wn$(1$\sigma$) which correspond to $\Delta\lambda/\lambda \sim 4 \times 10^{-7}$. This extensive laboratory database is of relevance for comparison with astronomical observations of H$_2$ and HD spectra from highly redshifted objects, with the goal of extracting a possible variation of the proton-to-electron mass ratio ($\mu=m_p/m_e$) on a cosmological time scale. For this reason also calculations of the so-called sensitivity coefficients $K_i$ were performed in order to allow for deducing constraints on $\Delta\mu/\mu$. The $K_i$ coefficients, associated with the line shift that each spectral line undergoes as a result of a varying value for $\mu$, were derived from calculations as a function of $\mu$ solving the Schr\"{o}dinger equation using \emph{ab initio} potentials.
Domaines
Physique [physics]
Origine : Fichiers produits par l'(les) auteur(s)
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