Additional Measurements and Analyses of H2

17O and H218O

June 22-25, 2015 ISMS

John. C. Pearson, Shanshan Yu, Adam DalyJet Propulsion Laboratory, California Institute of Technology,

Pasadena, CA 91109 USA

Adam WaltersIRAP, Université de Toulouse 3 - CNRS - OMP, Toulouse, France

Copyright 2015. All rights reserved.

• The rotational transitions of H2O (Yu et al. 2012)and D2O (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 H217O and H2

18O 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 D2O or H2O

Motivation

Herschel Spectra

31,2-30,3 16O

31,2-30,3 18O

11,1-00,0 18O

31,2-30,3 17O

11,1-00,0 17O

11,1-00,0 16O

Blue wing absorption in 11,1-00,0 is real (outflow)Several components are optically thick even in 17O!

A three step approach was adopted1. Re-measure or measure mW transitions in range of

spectrometer below 2.75 THz– Hyperfine had only been reported on a few 17O 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 17O 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 18O is 1/490 17O is 1/2703

• 17O enriched 10% sample also had 30% 18O– Water lines span many orders of magnitude in intensity (very optically

thick to very weak)

Measurements

Water afterPurging well!

Power SpectrumModulated very thick line 52,3-51,4 17O

Typical Spectra of Strong Lines

52,3-51,4 17O made thin <1mtorr

52,4-51,5 17O 2.67 THz41,4-30,3 18O 2.62 THz

22,1 11,0 18O 2.74 THz

• Lamb-dip measurements Puzzarini et al. 2009• 66 lines measured in this work• TuFIR from Matsushima et al. 1999• Historical microwave measurement where not replaced by

lamb-dip data• Infrared pure rotation (IUPAC list checked vs literature)• Infrared n2 band (IUPAC list checked vs literature)• Total of 2399 lines

17O Data

• Lamb-dip measurements Golubiatnikov et al. 2006• 63 lines measured in this work• TuFIR from Matsushima et al. 1999• Historical microwave measurement where not replaced by

lamb-dip data• Infrared pure rotation (IUPAC list checked vs literature)• Infrared n2 band (IUPAC list checked vs literature)

• New IR n2 band Oudot et al. 2012• Total of 3342 lines

18O Data

Euler Hamiltonians

Symmetric part of the Hamiltonian:

Parameters Dm,n relate to the usual distortion constants as follows:

The fixed constants av and bv must be chosen

D10=A, D01=(B+C)/2

Expansion variableJ(J+1)-K2

The asymmetry part of the Hamiltonian:

Anti-Symmetric part

Once again a’v and b’v are fixed parameters

d00=(B-C)/4

17O Analysis

Par GS Unct Exp v=1 Unct Exp Par GS Unct Exp v=1 Unct Expb_J 0.1 fixed 0.1 fixed a_K 1.3 fixed 3.34 fixedb'_J 0.1 fixed 0.1 fixed a'_K 4.5 fixed 6.68 fixedE 47706746.655 (231) d00 39460.6 (42) 41797.6 (59)D01 356431.0171 (61) 356678.1836 (316) d01 -15.22914 (219) -17.096 (99)D10 830283.7745 (74) 926902.785 (73) d10 122.63 (51) 150.5 (74)D02 -37.57026 (66) -41.9978 (71) d02 8.2815 (195) E-03 7.42 (80) E-03D11 560.56611 (303) 1339.733 (53) d11 -0.14061 (266) -0.624 (121)D20 252.24531 (229) 1558.61 (41) d20 1.429 (103) 2.96 (150)D03 0.016433 (304) 0.0213 (38) d03 -6.19 (36) E-06 0.0212 (65) E-03D12 -0.104616 (291) -0.1674 (71) d12 0.1057 (157) E-03 3.94 (89) E-03D21 0.26805 (53) 3.4926 (145) d21 -1.88 (52) E-03 0.071 (233)D30 2.48614 (36) 10.9296 (89) d30 -0.0125 (77) 0.06 (111)D04 -8.82 (71) E-06 -5.3 (90) E-06 d04 8.4 (39) E-09 -0.264 (59) E-06D13 0.1142 (103) E-03 1.14 (237) E-03 d13 -0.429 (126) E-06 -0.0208 (44) E-03D22 -2.173 (51) E-03 -0.14 (209) E-03 d22 1.78 (248) E-06 -0.664 (150) E-03D31 3.86 (58) E-03 0.01913 (144) d31 0.085 (37) E-03 -4.63 (153) E-03D40 -0.0105665 (309) -0.03753 (76) d40 0.457 (262) E-03 -2.9 (36) E-03

Partial list of parametersN=2399Reduced RMS 1.78

D10=A, D01=(B+C)/2

18O Analysis

Par GS Unc Exp v=1 Unc Exp Par GS Unc Exp v=1 Unc Expb_J 0.22 fixed E-03 0.22 fixed a_K 2.00 fixed E-03 3.34 fixed E-03b'_J 0.46 fixed E-03 0.46 fixed a'_K 4.00 fixed E-03 6.68 fixed E-03E 47615314.84 (210) d00 39603.30 (162) 41938.21 (130)D01 356152.10 (52) 356391.87 (134) d01 2.97 (106) 1.76 (178)D10 825367.23 (117) 921279.44 (48) d10 102.24 (200) 133.77 (161)D02 40.80 (48) 36.45 (228) d02 2.79 (159) E-03 4.69 (111) E-03D11 990.24 (263) 1539.81 (234) d11 -0.02 (118) 0.03 (214)D20 833.81 (260) 1561.16 (237) d20 1.73 (40) 7.03 (33)D03 0.02 (199) 0.02 (80) d03 -1.99 (33) E-06 -3.26 (45) E-06D12 0.24 (243) 0.50 (182) d12 -0.19 (109) E-03 -1.31 (132) E-03D21 1.60 (44) 4.25 (39) d21 -2.44 (220) E-03 -0.02 (41)D30 3.20 (273) 10.66 (42) d30 -0.05 (310) -0.25 (244)D04 -3.96 (41) E-06 -2.65 (112) E-06 d04 0.02 (41) E-06 6.25 (112) E-09D13 0.13 (81) E-03 0.23 (41) E-03 d13 0.98 (105) E-06 4.02 (60) E-06D22 -1.99 (46) E-03 -0.01 (45) d22 0.02 (165) E-03 0.18 (209) E-03D31 7.84 (44) E-03 0.03 (307) d31 0.23 (151) E-03 1.82 (265) E-03D40 -4.22 (162) E-03 -0.03 (303) d40 1.66 (113) E-03 7.10 (77) E-03

Partial list of parametersN=3342Reduced 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