Knowledge Bank

The microwave spectrum of $(H2O)2$ has been measured between 14 and 110 GHz using a newly developed electric-resonance optothermal spectrometer (EROS) described here. The reported measurements extend previous results on the a-type $Ka=0-0$ and 1-1 bands for the $A2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>},B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$, and $E\pm$ rotational-tunneling states and include the first observations of the c-type $Ka=1-0$ band for the $A2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ and $B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states and the a-type $Ka=0-0$ band for the $A1\pm$ states. For the $A1\pm$ states an interconversion tunneling splitting of 22.6 GHz is obtained, compared to the 19.5 GHz value found previously for the $Ka=0A2\pm$ and $B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states.