Sensitivity to a possible variation of the proton-to-electron mass ratio of torsion-rotation transitions in acetone (CH3)2CO

The notion that certain transitions of molecules with intramolecular large amplitude motions exhibit an enhanced sensitivity to the proton-to-electron mass ratio variation is changing the paradigm for searching for drifting constants from the optical to the microwave domain. It also stimulates a search for the new molecules that possess enhanced sensitivities to a variation of the proton-to-electron mass ratio. In this paper, we calculate the sensitivity coefficients for acetone, a molecule of astrophysical interest having a C-2v equilibrium configuration with two equivalent methyl tops undergoing internal rotation. The calculations were done for rotational transitions belonging to the ground and the first excited (v(12) approximate to 75 cm(-1)) torsional states of acetone, since both these states were detected during observations of interstellar molecular clouds. For rotational transitions with linestrengths above 1.0 and lower-level rotation excitation energies below 10 cm(-1) the sensitivity coefficients in this molecule range from K-mu = -0.69 to -1.23 for the ground state and from K-mu = -1.98 to +6.07 for the first excited torsional state. (C) 2014 Elsevier Inc. All rights reserved.