Laser and synchrotron spectroscopic studies of molecular hydrogen

Ubachs, W.M.G. [Promotor]Salumbides, E.J. [Copromotor

VUV spectroscopic study of the D1Piu state of molecular deuterium

The D^1\Pi_u - X^1\Sigma_g^+ absorption system of molecular deuterium has been re-investigated using the VUV Fourier -Transform (FT) spectrometer at the DESIRS beamline of the synchrotron SOLEIL and photon-induced fluorescence spectrometry (PIFS) using the 10 m normal incidence monochromator at the synchrotron BESSY II. Using the FT spectrometer absorption spectra in the range 72 - 82 nm were recorded in quasi static gas at 100 K and in a free flowing jet at a spectroscopic resolution of 0.50 and 0.20 cm^{-1} respectively . The narrow Q-branch transitions, probing states of \Pi^- symmetry, were observed up to vibrational level v = 22. The states of \Pi^+ symmetry, known to be broadened due to predissociation and giving rise to asymmetric Beutler-Fano resonances, were studied up to v = 18. The 10 m normal incidence beamline setup at BESSY II was used to simultaneously record absorption, dissociation, ionization and fluorescence decay channels from which information on the line intensities, predissociated widths, and Fano q-parameters were extracted. R-branch transitions were observed up to v = 23 for J = 1-3 as well as several transitions for J = 4 and 5 up to v = 22 and 18 respectively. The Q-branch transitions are found to weakly predissociate and were observed from v = 8 to the final vibrational level of the state v = 23. The spectroscopic study is supported by two theoretical frameworks. Results on the \Pi^- symmetry states are compared to ab initio multi-channel-quantum defect theory (MQDT) calculations, demonstrating that these calculations are accurate to within 0.5 cm^-1.Comment: 16 pages, 10 figures, 2 tables, supplemental material with an additional tabl

The D-1 Pi(u) state of HD and the mass scaling relation of its predissociation widths

Absorption spectra of HD have been recorded in the wavelength range of 75-90nm at 100K using the vacuum ultraviolet Fourier transform spectrometer at the Synchrotron SOLEIL. The present wavelength resolution represents an order of magnitude improvement over that of previous studies. We present a detailed study of the

VUV spectroscopic study of the B '' (B)over-bar(1) Sigma(+)(u) state of H-2

Spectral lines, probing rotational quantum states J′ = 0, 1, 2 of the inner well vibrations (υ′ ≤ 8) in the state of molecular hydrogen, were recorded in high resolution using a vacuum ultraviolet Fourier transform absorption spectrometer in the wavelength range 73-86 nm. Accurate line positions and predissociation widths are determined from a fit to the absorption spectra. Improved values for the line positions are obtained, while the predissociation widths agree well with previous investigations. © 2014 Taylor and Francis

Precision spectroscopy of the X-1 Sigma(+)(g), v=0 -> 1(J=0-2) rovibrational splittings in H-2, HD and D-2

Accurate experimental values for the vibrational ground tone or fundamental vibrational energy splitting of

The excited J=0 (1)Sigma(+)(u) levels of D-2: Measurements and ab initio quantum defect study

International audienceThe DESIRS beamline of the SOLEIL synchrotron facility, equipped with a vacuum ultraviolet Fourier-transform spectrometer has been used to measure P(N″=1)P(N″=1) (N-N″=-1N-N″=-1) absorption transitions of the D2 molecule. Some 44 P-lines were assigned and their transition frequencies determined up to excitation energies of 134000 cm−1 above the ground state, thereby extending the earlier work by various authors, and considerably improving the spectral accuracy (<0.1<0.1 cm−1). The assignments have been aided by first principles multichannel quantum defect theory (MQDT) calculations. These calculations also provide predictions of the autoionization widths of the upper levels which agree well with the observed resonance widths

Precision spectroscopy of high rotational states in H-2 investigated by Doppler-free two-photon laser spectroscopy in the EF (1)Sigma(+)(g)-X (1)Sigma(+)(g) system

Recently a high precision spectroscopic investigation of the EF1 Sigma(+)(g)-X-1 Sigma(+)(g) system of molecular hydrogen was reported yielding information on QED and relativistic effects in a sequence of rotational quantum states in the X-1 Sigma(+)(g) ground state of the H-2 molecule [Salumbides et al., Phys. Rev. Lett. 107, 043005 (2011)]. The present paper presents a more detailed description of the methods and results. Furthermore, the paper serves as a stepping stone towards a continuation of the previous study by extending the known level structure of the EF1 Sigma(+)(g) state to highly excited rovibrational levels through Doppler-free two-photon spectroscopy. Based on combination differences between vibrational levels in the ground state, and between three rotational branches (O, Q, and S branches) assignments of excited EF1 Sigma(+)(g) levels, involving high vibrational and rotational quantum numbers, can be unambiguously made. For the higher EF1 Sigma(+)(g) levels, where no combination differences are available, calculations were performed using the multichannel quantum defect method, for a broad class of vibrational and rotational levels up to J = 19. These predictions were used for assigning high-J EF levels and are found to be accurate within 5 cm(-1)

Fundamental vibration of molecular hydrogen.

The fundamental ground tone vibration of

VUV Fourier-Transform absorption study of the npπnpπ1Πu-,v,N←X1Σg+,v″=0,N″ transitions in D2

International audienceThe DESIRS beamline of the SOLEIL synchrotron facility, equipped with a vacuum ultraviolet Fourier-Transform spectrometer has been used to measure Q(N″)Q(N″) (N-N″=0N-N″=0) absorption transitions of the D2 molecule. Some 212 Q-lines were assigned and their transition frequencies determined up to excitation energies of 137000 cm-1 above the ground state, thereby extending the earlier work by various authors, and considerably improving the spectral accuracy (<0.1<0.1 cm-1). The assignments have been aided by first principles multichannel quantum defect theory (MQDT) calculations which also provide predictions of the autoionization widths of the upper levels

Fourier-transform spectroscopy of HD in the vacuum ultraviolet at lambda = 87-112 nm

International audienceAbsorption 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