Enhanced sensitivity to a possible variation of the proton-to-electron mass ratio in ammonia

0461240 - ÚOCHB 2017 RIV US eng J - Journal Article
Owens, A. - Yurchenko, S. N. - Thiel, W. - Špirko, Vladimír
Enhanced sensitivity to a possible variation of the proton-to-electron mass ratio in ammonia.
Physical Review A. Roč. 93, č. 5 (2016), č. článku 052506. ISSN 2469-9926. E-ISSN 2469-9934
Institutional support: RVO:61388963
Keywords : precision measurements * polyatomic molecules * accurate prediction
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 2.925, year: 2016

Numerous accidental near degeneracies exist between the 2.2 and.4 rotation-vibration energy levels of ammonia. Transitions between these two states possess significantly enhanced sensitivity to a possible variation of the proton-to-electron mass ratio mu. Using a robust variational approach to determine the mass sensitivity of the energy levels along with accurate experimental values for the energies, sensitivity coefficients have been calculated for over 350 microwave, submillimeter, and far-infrared transitions up to J = 15 for (NH3)-N-14. The sensitivities are the largest found in ammonia to date. One particular transition, although extremely weak, has a sensitivity of T = -16 738 and illustrates the huge enhancement that can occur between close-lying energy levels. More promising however are a set of previously measured transitions with T = -32 to 28. Given the astrophysical importance of ammonia, the sensitivities presented here confirm that (NH3)-N-14 can be used exclusively to constrain a spatial or temporal variation of mu. Thus certain systematic errors which affect the ammonia method can be eliminated. For all transitions analyzed we provide frequency data and Einstein A coefficients to guide future laboratory and astronomical observations.
Permanent Link: http://hdl.handle.net/11104/0260952