Testing the time-invariance of fundamental constants using microwave spectroscopy on cold diatomic radicals

Bethlem, Hendrick L.; Ubachs, Wim

doi:10.1039/b819099b

Cited by 55 publications

(73 citation statements)

References 31 publications

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“…For instance, molecules in electronic states with nonzero electronic angular momentum have fine-structure splittings that are comparable to vibrational splittings in heavy molecules 31 and to rotational splittings in light molecules. 32 Likewise, molecules that possess nuclear spin have hyperfine splittings that can be comparable to rotational splittings. 33 In polyatomic molecules, splittings due to classically forbidden large-amplitude motions, such as inversion [34][35][36] or internal rotation, 24,37 can be comparable to rotational splittings.…”

Section: Definition Of Sensitivity Coefficientsmentioning

confidence: 99%

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

Jansen

Bethlem

Ubachs

2014

The Journal of Chemical Physics

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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: Definition Of Sensitivity Coefficientsmentioning

confidence: 99%

“…This problem disappears when two-photon transitions are considered, as was done by Bethlem and Ubachs 32 for CO in its metastable a 3 state, which is perhaps the best studied excited triplet system of any molecule. [70][71][72][73] On the right-hand side of Fig.…”

Section: B Near-degeneracies In Diatomic Radicalsmentioning

confidence: 99%

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

Jansen

Bethlem

Ubachs

2014

The Journal of Chemical Physics

Self Cite

114

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“…The reference potentials U ref i (r) approach the true potential at long range, and μ is the reduced mass. They include the centrifugal termsh 2 …”

Section: Theorymentioning

confidence: 99%

“…These include high-precision measurement [1,2], quantum information processing [3], and quantum simulation [4]. There is also great interest in the development of controlled ultracold chemistry [5].…”

Section: Introductionmentioning

confidence: 99%

Optimized multichannel quantum defect theory for cold molecular collisions

2012

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Multichannel quantum defect theory (MQDT) can provide an efficient alternative to full coupled-channel calculations for low-energy molecular collisions. However, the efficiency relies on interpolation of the Y matrix that encapsulates the short-range dynamics, and there are poles in Y that may prevent interpolation over the range of energies of interest for cold molecular collisions. We show how the phases of the MQDT reference functions may be chosen so as to remove such poles from the vicinity of a reference energy and dramatically increase the range of interpolation. For the test case of Mg + NH, the resulting optimized Y matrix may be interpolated smoothly over an energy range of several Kelvin and a magnetic field range of over 1000 gauss. Calculations at additional energies and fields can then be performed at a computational cost that is proportional to the number of channels N and not to N 3 .

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“…There is now great interest in producing samples of cold molecules, at temperatures below 1 K [3][4][5], and ultracold molecules, at temperatures below 1 mK [6][7][8][9]. There are many potential applications of ultracold molecular samples, amongst which are highprecision measurements [10,11], quantum computation [12], and ultracold chemistry [13].…”

Section: Introductionmentioning

confidence: 99%

Multichannel quantum defect theory for cold molecular collisions

et al. 2011

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'Multichannel quantum defect theory for cold molecular collisions. ', Physical review A., 84 (4). 042703.Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Multichannel quantum defect theory (MQDT) is shown to be capable of producing quantitatively accurate results for low-energy atom-molecule scattering calculations. With a suitable choice of reference potential and short-range matching distance, it is possible to define a matrix that encapsulates the short-range collision dynamics and is only weakly dependent on energy and magnetic field. Once this has been produced, calculations at additional energies and fields can be performed at a computational cost that is proportional to the number of channels N and not to N 3 . MQDT thus provides a promising method for carrying out low-energy molecular scattering calculations on systems where full exploration of the energy dependence and the field dependence is currently impractical.

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Testing the time-invariance of fundamental constants using microwave spectroscopy on cold diatomic radicals

Cited by 55 publications

References 31 publications

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

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

Optimized multichannel quantum defect theory for cold molecular collisions

Multichannel quantum defect theory for cold molecular collisions

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