Dimethyl Ether: Laboratory Assignments and Predictions through 600 GHz

Abstract

Dimethyl ether is a well-known interstellar molecule with a large abundance in hot core (CH 3 OCH 3 ) regions. We have measured many rotational-torsional transition lines of this molecule in the 100550 GHz frequency range using two experimental techniques : a klystron-based traditional millimeter-wave spectrometer and a new fast scan spectrometer (designated "" FASSST ) with a voltage-tunable backward wave oscillator. The lines arising from the ground vibrational state have been combined with previous data, mainly at lower frequencies, to form a global data set consisting of over 1600 lines that have been assigned and tted by an e ective Hamiltonian method. The spectral constants obtained from the t allow us to predict the frequencies of almost 6000 additional lines of dimethyl ether through 600 GHz.