Sensitivity to electron-to-proton mass ratio variation from 12C2H2 rovibrational transitions to v1 + v3 and v1 + v2 + v4 + v5 interacting levels

Calculations of the sensitivity to a variation of the electron-to-proton mass ratio mu for (C2H2)-C-12 transitions of the v(1) +v(3) and v(1) + v(2) + v(4) + v(5) bands in the spectral region at 1.5 mu m are presented. They account for the Fermi and l-type rotation and vibration resonances of the excited states. The frequency splittings between near resonant transitions, arising from a cancellation of effective rotational intervals with frequency shifts associated to the vibrational band origin, the anharmonicity and the rotation-vibration interactions, have sensitivity coefficients to a variation of mu of both signs in the range of 10-10(3). The measurements of temporal drifts of frequency splittings against the Cs frequency standard have the potential to better constrain a variation of mu comparing to that of other fundamental constants. The systematic frequency shifts for frequency splittings are discussed for experimental setups based on intracavity saturated absorption spectroscopy and the constraint of a measurement of a fractional variation of mu is projected at 10(-10) level. (C) 2016 Elsevier B.V. All rights reserved.