High-resolution VUV-laser spectroscopic study of the B1Σ+(u)(v′ = 0–2)← X1Σ+(g)(v″ = 0) Lyman bands in H2and HD

Hollenstein, U.; Reinhold, E.M.; Lange, C.A. de; Ubachs, Wim

doi:10.1088/0953-4075/39/8/l02

Cited by 27 publications

(41 citation statements)

References 34 publications

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“…[52][53][54] Similar investigations of the XUV-laser spectrum of HD were performed in view of the fact that HD lines were also observed in high-redshift spectra towards quasar sources. 55,56 Additional spectroscopic studies of H 2 were performed assessing the level energies in these excited states in an indirect manner, thereby verifying and even improving the transition frequencies in the Lyman and Werner bands. 57,58 The data set of laboratory wavelengths obtained for both H 2 and HD, has reached an accuracy that can be considered exact for the purpose of comparison with quasar data, where accuracies are never better than 10 −7 .…”

Section: A Transitions In Molecular Hydrogen and Carbon Monoxidementioning

confidence: 99%

Perspective: Tipping the scales: Search for drifting constants from molecular spectra

Jansen

Bethlem

Ubachs

2014

The Journal of Chemical Physics

114

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Precision measurement of the rotational energy-level structure of the three-electron molecule He 2 + Transitions in atoms and molecules provide an ideal test ground for constraining or detecting a possible variation of the fundamental constants of nature. In this perspective, we review molecular species that are of specific interest in the search for a drifting proton-to-electron mass ratio μ.In particular, we outline the procedures that are used to calculate the sensitivity coefficients for transitions in these molecules and discuss current searches. These methods have led to a rate of change in μ bounded to 6 × 10 −14 /yr from a laboratory experiment performed in the present epoch. On a cosmological time scale, the variation is limited to | μ/μ| < 10 −5 for look-back times of 10-12 × 10 9 years and to | μ/μ| < 10 −7 for look-back times of 7× 10 9 years. The last result, obtained from high-redshift observation of methanol, translates intoμ/μ = (1.4 ± 1.4) × 10 −17 /yr if a linear rate of change is assumed.

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Section: A Transitions In Molecular Hydrogen and Carbon Monoxidementioning

confidence: 99%

Perspective: Tipping the scales: Search for drifting constants from molecular spectra

Jansen

Bethlem

Ubachs

2014

The Journal of Chemical Physics

114

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“…Later the lines probing the lowest v 0 Lyman bands in the wavelength range 108-110 nm were investigated in detail [90]; the I 2 saturation reference lines were not covered in our own calibration program [86,87], but fortunately the reference standard produced by the Hannover group was made available to us during the course of the investigations [91], thus allowing for calibration at the 0.005 cm À1 level. Due to lower efficiencies of laser dyes in the range 650-660 nm the XUV-intensity level was lower than at shorter wavelengths.…”

Section: H 2 Spectroscopy In the Laboratorymentioning

confidence: 99%

“…For the methods for determining the absolute uncertainties in the line centers, the assessment of the error budget including frequency chirp in the PDA, treatment of possible Doppler shifts in the crossed beam experiments, and possible ACStark induced shifts we refer to the experimental sections of Refs. [85,88,90]. In the top part a continuous wave ring-dye laser produces a stable carrier frequency of 1 MHz bandwidth; its absolute frequency is calibrated against an I 2 reference standard, while relative frequency spacings are measured with respect to an etalon, stabilized to an HeNe laser.…”

Section: H 2 Spectroscopy In the Laboratorymentioning

confidence: 99%

“…This is the generic setup. As discussed in the text some variations on this scheme are used to perform measurements on some wavelength regions, involving mixing with the 532 nm output of a Nd:YAG laser [89], addition of a short wavelength ionization laser [90], and using a sum-frequency mixing scheme for the production of XUV light [92]. PBS: polarizing beam splitter; PD: photodiode.…”

Section: H 2 Spectroscopy In the Laboratorymentioning

confidence: 99%

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On a possible variation of the proton-to-electron mass ratio: H2 spectra in the line of sight of high-redshift quasars and in the laboratory

Ubachs

Buning

Eikema

et al. 2007

Journal of Molecular Spectroscopy

124

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Recently the finding of an indication for a decrease of the proton-to-electron mass ratio l = m p /m e by 0.002% in the past 12 billion years was reported in the form of a Letter [E. Reinhold, R. Buning, U. Hollenstein, P. Petitjean, A. Ivanchik, W. Ubachs, Phys. Rev. Lett. 96 (2006) 151101]. Here we will further detail the methods that led to that result and put it in perspective. Laser spectroscopy on molecular hydrogen, using a narrow-band and tunable extreme ultraviolet laser system at the Laser Centre Vrije Universiteit Amsterdam, results in transition wavelengths of spectral lines in theWerner band systems at an accuracy of (4-11) · 10 À8, depending on the wavelength region. This corresponds to an absolute accuracy of 0.000004-0.000010 nm. A database of 233 accurately calibrated H 2 lines is presented here for future reference and comparison with astronomical observations. Recent observations of the same spectroscopic features in cold hydrogen clouds at redshifts z = 2.5947325 and z = 3.0248970 in the line of sight of two quasar light sources (Q 0405À443 and Q 0347À383) resulted in 76 reliably determined transition wavelengths of H 2 lines at accuracies in the range 2 · 10 À7 to 1 · 10 À6 . Those observations were performed with the Ultraviolet and Visible Echelle Spectrograph at the Very Large Telescope of the European Southern Observatory at Paranal, Chile. A third ingredient in the analysis is the calculation of an improved set of sensitivity coefficients K i , a parameter associated with each spectral line, representing the dependence of the transition wavelength on a possible variation of the proton-to-electron mass ratio l. The new model for calculation of the K i sensitivity coefficients is based on a Dunham representation of ground state and excited state level energies, derived from the most accurate data available in literature for the X 1 R þ g ground electronic state and the presently determined level energies in the B 1 R þ u and C 1 P u states. Moreover, the model includes adiabatic corrections to electronic energies as well as local perturbation effects between B and C levels. The full analysis and a tabulation of the resulting K i coefficients is given in this paper. A statistical analysis of the data yields an indication for a variation of the proton-to-electron mass ratio of Dl/l = (2.45 ± 0.59) · 10 À5 for a weighted fit and Dl/l = (1.99 ± 0.58) · 10 À5 for an unweighted fit. This result, indicating the decrease of l, has a statistical significance of 3.5r. Mass-variations as discussed relate to inertial or kinematic masses, rather than gravitational masses. Separate treatment of the data gives a similar positive result for each of the quasars Q 0405À443 and Q 0347À383. The statistical analysis is further documented and possible systematic shifts underlying the data, with the possibility of mimicking a non-zero Dl/l value, are discussed. The observed decrease in l corresponds to a rate of change of d lnl/dt = À2 · 10 À15 per year, if a linear variation with time is assumed. Expe...

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“…The absolute frequency calibration is derived from a reference standard in the visible range, based on saturation spectroscopy of molecular iodine [10]; interpolation is performed with the use of a stabilized e´talon and the calibration in the XUV-domain is then derived from multiplication by the harmonic order. The full analysis of the uncertainty budget of the XUV-spectroscopic measurements has been discussed in recent studies performed by the group of the Laser Center, for limited sets of rotational lines of Lyman and Werner bands in H 2 and HD [11][12][13] and for the recently published work on freqency calibration of Lyman transitions in H 2 [14]. In Figure 1 a typical recording of a D 2 spectral line is displayed, with the I 2 and e´talon traces used for the calibration.…”

Section: Methodsmentioning

confidence: 99%

Extreme ultraviolet laser calibration of D_2Lyman and Werner transitions

et al. 2008

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High-resolution VUV-laser spectroscopic study of the B¹Σ⁺_(u)(v′ = 0–2)← X¹Σ⁺_(g)(v″ = 0) Lyman bands in H₂and HD

Cited by 27 publications

References 34 publications

Perspective: Tipping the scales: Search for drifting constants from molecular spectra

Perspective: Tipping the scales: Search for drifting constants from molecular spectra

On a possible variation of the proton-to-electron mass ratio: H2 spectra in the line of sight of high-redshift quasars and in the laboratory

Extreme ultraviolet laser calibration of D_2Lyman and Werner transitions

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