1. A Search for Interstellar H2DO+
Christopher P. Morong
Department of Chemistry, University of Chicago
Shuji Saito, Takashi Furuya
Research Center for Development of Far-Infrared Region,
Fukui University, Fukui, Japan
Hiroko Shinnaga
Caltech Submillimeter Observatory
Takeshi Oka
Department of Astronomy and Astrophysics, and Department of Chemistry, University of Chicago
63rd Ohio State University International Symposium on Molecular Spectroscopy

2. Why H2DO+? Galactic D/H~10-5
Special conditions deuterium fractionation >104
CO and N2 freeze onto grain surfaces
NH3 and N2H+ survive in gas phase in highly depleted cores
OH, H2O and H3O+ may also survive in gas phase
If atomic oxygen does not stick efficiently to grain surfaces
Probe of oxygen chemistry in clouds
Less atmospheric interference

3. H2DO+ Formation *
*Cold dense clouds

4. H2DO+ Experiment Stainless steel hollow-cathode
1.1 m long
2.4 Pa H2O Pa D2O
400 mA
Tcell~240 K
Isotopic, magnetic
(ion/neutral) and
temperature discrimination
T. Furuya, S. Saito and M. Araki, J. Chem. Phys, 127, (2007)

5. H2DO+ Energy Levels
~ 60 K
T. Furuya, S. Saito and M. Araki, J. Chem. Phys, 127, (2007)

6. H3O+ Transitions
Phillips et al., Astrophysical. J. 399 (1992) 533

7. 1.3 mm continuum
Mott et al., A&A 336 (1998)
Huang et al., Adv. Space Research 36 (2005)

8. IRAS 16293-2422 ~120 pc from Earth in the  Ophiuchus cloud complex
+4.0 km/s
Protobinary system
~600 AU
Inside L1689N
Class 0 protostar
Luminosity ~ 27 L
Mass ~ 1.1 M
Temperature ~ K
Density cm-3
~30,000 years collapsing
years old (evaporation of the mantles)
Wakelam et al. A&A 413 (2004) 609

9. IRAS 16293-2422 CH3OD 2% CH2DOH 30% HDO 3% HDCO 15% D2O 0.005% CHD2OH6%
D2CO 5%
CD3OH
1.4%
HCO+, CH3OCHO, CH3OCH3, HCOOH, CH3COOH, CH3CHO, CH3CN, CH3CCH, C2H5CN, SO, SO2, HCN, HNC, OCS, H2CS, CH2CDCN…

10. Caltech Submillimeter Observatory
10.4-m hexagonally-segmented Leighton dish
Heterodyne SIS receivers
230, 345, 490 and 665 GHz atmospheric windows

11. Atmospheric Transmission

12. Observation Conditions

13. Results (19.17 minutes)

14. Future
The search continues
Hope for dry weather