Additional Measurements and Analyses of H 2 17 O and H 2 18 O June 22-25, 2015 ISMS John. C. Pearson, Shanshan Yu, Adam Daly Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA Adam Walters IRAP, Université de Toulouse 3 - CNRS - OMP, Toulouse, France Copyright All rights reserved.

The rotational transitions of H 2 O (Yu et al. 2012)and D 2 O (Bruenken et al. 2007) can be modeled to nearly experimental accuracy RMS 1.2 & 1.4 with an Euler series Hamiltonian (Pickett et al. 2005) However similar attempts for H 2 17 O and H 2 18 O resulted in far a significantly poorer RMS 5-10 – Impossible to predict transitions with desired accuracy The accepted line list from the IUPAC review (Tennyson et al. 2009) did not improve the fit much – Poorer than reported data? – Unexpected model problems? We wished to be able to model and predict the spectrum comparably well to D 2 O or H 2 O Motivation

Herschel Spectra 3 1,2 -3 0,3 16 O 3 1,2 -3 0,3 18 O 1 1,1 -0 0,0 18 O 3 1,2 -3 0,3 17 O 1 1,1 -0 0,0 17 O 1 1,1 -0 0,0 16 O Blue wing absorption in 1 1,1 -0 0,0 is real (outflow) Several components are optically thick even in 17 O!

A three step approach was adopted 1.Re-measure or measure mW transitions in range of spectrometer below 2.75 THz – Hyperfine had only been reported on a few 17 O transitions 2.Critically review the existing data sets using Euler series models – Start with IUPAC review but check against previous work – Validate/update the experimental uncertainties – Identify poor measurement 3.Make predictions with better precision – Including hyperfine in 17 O water Approach

THz measurements of water pose a few challenges – Atmospheric lines absorb all the power in spots Solve by purging the air path – Isotopic abundance small 18 O is 1/ O is 1/ O enriched 10% sample also had 30% 18 O – Water lines span many orders of magnitude in intensity (very optically thick to very weak) Measurements Water after Purging well! Power SpectrumModulated very thick line 5 2,3 -5 1,4 17 O

Typical Spectra of Strong Lines 5 2,3 -5 1,4 17 O made thin <1mtorr 5 2,4 -5 1,5 17 O 2.67 THz 4 1,4 -3 0,3 18 O 2.62 THz 2 2,1 1 1,0 18 O 2.74 THz

Lamb-dip measurements Puzzarini et al lines measured in this work TuFIR from Matsushima et al Historical microwave measurement where not replaced by lamb-dip data Infrared pure rotation (IUPAC list checked vs literature) Infrared 2 band (IUPAC list checked vs literature) Total of 2399 lines 17 O Data

Lamb-dip measurements Golubiatnikov et al lines measured in this work TuFIR from Matsushima et al Historical microwave measurement where not replaced by lamb-dip data Infrared pure rotation (IUPAC list checked vs literature) Infrared 2 band (IUPAC list checked vs literature) New IR 2 band Oudot et al Total of 3342 lines 18 O Data

Euler Hamiltonians Symmetric part of the Hamiltonian: Parameters D m,n relate to the usual distortion constants as follows: The fixed constants a v and b v must be chosen D 10 =A, D 01 =(B+C)/2 Expansion variable J(J+1)-K 2

The asymmetry part of the Hamiltonian: Anti-Symmetric part Once again a’ v and b’ v are fixed parameters d 00 =(B-C)/4

17 O Analysis Partial list of parameters N=2399 Reduced RMS 1.78 D 10 =A, D 01 =(B+C)/2

18 O Analysis Partial list of parameters N=3342 Reduced RMS 1.42

A significant number of Infrared and a few of the historical microwave measurements were found to be of substantially poorer that stated – Many could be identified trivially due to differences with other measurements Removal of these lines from the analysis enabled the remainder of the data to be fit to near experimental accuracy Rotational transitions in the ground state can now be predicted with sufficient accuracy to support velocity resolved astrophysical measurements e.g. comet isotopic ratio studies No surprises were found in the modeling Conclusions

A part of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration Acknowledgement