Knowledge Bank

Extensive microwave measurements have been made on the (D2O)2 using a pulsed-nozzle Fourier-transform microwave spectrometer and a recently developed electric-resonance Optothermal spectrometer (EROS). The new measurements build on the previous spectroscopic work of Odutola $etal.1$ and Coudert $etal.2$ for the $K=0A1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>},B1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$, and $E\pm$ states. Spectra have been recorded between 9 - 110 GHz and include the first observation of the $A2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ and $B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states. The tunneling splitting for the $K=0A2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}/B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states is determined to be 1083.303(21) MHz, which is slightly lower than the 1172.115(14) MHz value found previously for the $A1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}/B1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states. In addition, we report the first $K=1$ measurements on $(D2O)2$, giving a tunneling splittings of 1076.616(14) and 992.368(90) MHz for the $A1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}/B1\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ and $A2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}/B2\mathrm{<mrow\; data-mjx-texclass="ORD">\pm </mrow>}$ states, respectively. Searches have also been made for b or c-type $K=1-0$ transitions predicted near 100 GHz. A number of transitions have been observed but are presently unassigned.