Acetone: Laboratory Assignments and Predictions through 620 GH z for the Vibrational‐Torsional Ground State

Abstract

The acetone molecule has a complex rotational spectrum arising from the internal rotation of two methyl tops and their interaction with each other and the rigid-body rotation of the molecule. Here we report the measurement and assignment of a large number of new rotational-torsional transitions of acetone in the vibrational-torsional ground state at frequencies of up to 620 GHz. The newly measured lines have been combined with previously measured transition frequencies and fitted by a procedure used successfully for dimethyl ether. From the fit to the global data set, we have extracted parameters that have enabled us to predict accurately the frequencies and intensities of over 10,000 lines of possible astronomical importance at frequencies of up to 620 GHz. The detection of interstellar acetone was first reported by Combes et al. based on two transitions with partially resolved internal rotation structure. The present work will aid further interstellar studies to verify acetone as an interstellar constituent.