MICROWAVE ELECTRIC-RESONANCE OPTOTHERMAL SPECTROSCOPY OF $(H_{2}O)_{2}$

Author Institution: Molecular Spectroscopy Division, National Institute of Standards and TechnologyThe microwave spectrum of $(H_{2}O)_{2}$ 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 $K_{a}=0-0$ and 1-1 bands for the $A_{2}{^{\pm}}, B_{2}{^{\pm}}$, and $E^{\pm}$ rotational-tunneling states and include the first observations of the c-type $K_{a}=1-0$ band for the $A_{2}{^{\pm}}$ and $B_{2}{^{\pm}}$ states and the a-type $K_{a}=0-0$ band for the $A_{1}^{\pm}$ states. For the $A_{1}^{\pm}$ states an interconversion tunneling splitting of 22.6 GHz is obtained, compared to the 19.5 GHz value found previously for the $K_{a}=0 A_{2}^{\pm}$ and $B_{2}{^{\pm}}$ states