Additional measurements and analyses of H217O and H218O

Abstract

Historically the analysis of the spectrum of water has been a balance between the quality of the data set and the applicability of the Hamiltonian to a highly non-rigid molecule. Recently, a number of different non-rigid analysis approaches have successfully been applied to $^{16}$O water resulting in a self-consistent set of transitions and energy levels to high J which allowed the spectrum to be modeled to experimental precisionfootnote{SS. Yu, J.C. Pearson, B.J. Drouin textit{et al. J. Mol. Spectrosc.} textbf{279},~16-25 (2012)}footnote{J. Tennyson, P.F. Bernath, L.R. Brown textit{et al. J. Quant. Spectrosc. Rad. Trans.} textbf{117}, 29-58 (2013)}. The data set for $^{17}$O and $^{18}$O water was previously reviewed and many of the problematic measurements identifiedfootnote{J. Tennyson, P.F. Bernath, L.R. Brown textit{et al. J. Quant. Spectrosc. Rad. Trans.} textbf{110}, 573-596 (2009)}, but Hamiltonian modeling of the remaining data resulted in significantly poorer quality fits than that for the $^{16}$O parent. As a result, we have made additional microwave measurements and modeled the existing $^{17}$O and $^{18}$O data sets with an Euler series modelfootnote{H.M. Pickett, J.C. Pearson, C.E. Miller textit{J. Mol. Spectrosc.} textbf{233}, 174-179 (2005)}. This effort has illuminated a number of additional problematic measurements in the previous data sets and has resulted in analyses of $^{17}$O and $^{18}$O water that are of similar quality to the $^{16}$O analysis. We report the new lines, the analyses and make recommendations on the quality of the experimental data sets.