Sensitivity of microwave spectra of deuterated ammonia to variation of electron-to-proton mass ratio

TL;DR

This paper estimates how microwave spectra of deuterated ammonia molecules are sensitive to potential variations in the electron-to-proton mass ratio, aiding astrophysical searches for fundamental constant changes.

Contribution

It provides calculated sensitivity coefficients for microwave transitions in NH2D and ND2H, considering rotational-inversion mixing, which was not previously detailed.

Findings

Sensitivity coefficients vary with transition quantum numbers.

Mixing of rotational and inversion modes affects sensitivity.

Results support using ammonia spectra to probe fundamental constant variations.

Abstract

We estimate sensitivity coefficients Q_\mu to variation of the electron-to-proton mass ratio \mu for microwave transitions in partly deuterated ammonia NH2D and ND2H. Because of the mixing between rotational and inversion degrees of freedom the coefficients Q_\mu strongly depend on the quantum numbers of the transition. This can be used for astrophysical search for possible variation of the constant \mu.