Electric Dipole Moments of Acetone and of Acetic Acid Measured in Supersonic Expansion

Precise values for electric dipole moments of isolated acetone and acetic acid molecules were determined from the Stark effect measurements made on lowest J rotational transitions at conditions of supersonic expansion. The new results are $μ_{tot} =μ_b$ =2.9345(22) D for acetone from measurements on the $1_{11}$← $1_{01}$ transition, and $μ_a$ =0.8631(8), $μ_b$ =1.4345(11), $μ_{tot}$ =1.6741(10) D for acetic acid, from measurements on $1_{11}$ ← $0_{00}$ and $1_{01}$ ← $0_{00}$ transitions. A comparison with previous determinations and with results of quantum chemical calculations is presented.