Highly Sensitive Ammonia Probes of a Variable Proton-to-Electron Mass Ratio.
The mass sensitivity of the vibration-rotation-inversion energy levels of ammonia is probed using the nonrigid inverter theory. It is shown that the sensitivity exhibits non-negligible centrifugal distortion dependence, which is currently disregarded. The centrifugal distortion effects are especially important in the case of the Δk = ±3 "forbidden" transitions involving accidentally coinciding ro-inversional states |a,J,K = 3⟩ and |s,J,K = 0⟩ of the ν2 vibrational state of (14)NH3. The energy differences of these states exhibit very anomalous mass sensitivities (see Jansen etal. J. Chem. Phys. 2014 , 140 , 010901 ), thus appearing as new highly sensitive probes of the cosmological variability of the proton-to-electron mass ratio.
Academy of Sciences of the Czech Republic, Institute of Organic Chemistry and Biochemistry, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
Vladimír
V
Špirko
ISM molecules; ammonia; centrifugal distortion; inversion−rotation; proton-to-electron mass ratio; sensitivity coefficients