Electric dipole moment of sulfuric acid from Fourier transform microwave spectroscopy

The electric dipole moment of H2SO4 in the gas phase has been measured using pulsed-nozzle Fourier transform microwave spectroscopy. Ninety one Stark-shifted frequencies at a series of electric field strengths have been recorded for the 110 ← 000 transition. The total molecular dipole moment (μtot = μc) was determined to be 2.9643(67) D. This is approximately 0.24 D greater than the previous literature value obtained from similar measurements on the 643 ← 533 transition. Both ab initio and DFT calculations using Dunning's aug-cc-pVnZ (n = D, T, Q, Q+d) basis sets concur with the present result.