THE MILLIMETER/SUBMILLIMETER SPECTRUM AND ROTATIONAL REST FREQUENCIES OF MgCH_3(X ~2A_1)

摘要

The pure rotational spectrum of the free radical MgCH_3(X ~2A_1) has been measured in the laboratory for the first time using millimeter/submillimeter direct absorption spectroscopy. The molecule was made in a DC discharge by the reaction of magnesium vapor and dimethyl mercury. Ten rotational transitions of this species were observed in the range 176-374 GHz. MgCH_3 is a symmetric top molecule with net spin angular momentum. Consequently, both K structure and spin-rotation interactions were observed in every rotational transition. The data were analyzed with a ~2A_1 Hamiltonian and rotational, centrifugal distortion, and fine-structure parameters were accurately determined. These measurements will now enable a search for this radical in interstellar and circumstellar sources to be conducted using millimeter/submillimeter telescopes.