The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz Brandon Carroll 1 Brian Drouin 2 Susanna Widicus Weaver 1 June 22, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 1. Department of Chemistry, Emory University, Atlanta, GA 30322

Glycolaldehyde The simplest α-hydroxy aldehyde Detected in the ISM Possible insight into reaction pathways leading to formation of sugars, aldoses, and other prebiotic molecules in the ISM Substantial dipole moment (2.73D)

Previous Laboratory Work Microwave Spectrum – Marstökk and Møllendal (1971 & 1973) 1 – GHz, 49 lines assigned in the ground vibrational state – Lines from 3 excited vibrational states also assigned – Stark measurements of dipole moment – μ a = 0.12 D, μ b = 2.73 D Millimeter-Wave Spectrum – Butler et al. (2001) 2, Widicus Weaver et al. (2005) 3 – GHz, 1657 lines assigned in the ground vibrational state – Lines from 3 excited vibrational states also assigned 1. Marstökk, K. M., & Møllendal, H. 1970, J. Mol. Struct., 5, 205, Marstökk, K. M., & Møllendal, H. 1973, J. Mol. Struct., 16, Widicus Weaver S. L., Butler R. A. H., Drouin B. J., Petkie D. T., Dyl K. A., De Lucia F. C., & Blake G.A. "Millimeter-wave and vibrational state assignments for the rotational spectrum of glycolaldehyde." Astrophys. J. Suppl., 158, , Butler, R. A. H., De Lucia, F. C., Petkie, D. T., Møllendal, H., Horn, A., & Herbst, E. 2001, ApJS, 134, 319

ISM Detection Originally detected by Hollis et al. (2000) 1 in Sgr B2 (N-LMH) – Based on extrapolated microwave data. Detection confirmed by Halfen et al. (2006) 2 1. Hollis, J. M., Lovas, F. J., & Jewell, P. R. 2000, ApJ, 540, L D. T. Halfen, A. J. Apponi, N. Woolf, R. Polt, and L. M. Ziurys 2006, ApJ, 639:

New Observatories Herschel Space Observatory – 480 GHz THz, 1.4 THz THz Atacama Large Millimeter Array (ALMA) – 80 GHz GHz Stratospheric Observatory for Infrared Astronomy (SOFIA) – 500 GHz THz

High Frequency Observations 1. N. R. Crockett, E. A. Bergin, S. Wang, D. C. Lis, T. A. Bell, G.A. Blake E. Caux, C. Ceccarelli, J. Cernicharo, C. Comito, F. Daniel, M.-L. Dubernet, M. Emprechtinger, P. Encrenaz, M. Gerin, T. F. Giesen, J. R. Goicoechea, P. F. Goldsmith, H. Gupta, E. Herbst, C. Joblin, D. Johnstone, W. D. Langer, W.D. Latter S. D. Lord, S. Maret, P. G. Martin, G. J. Melnick, K. M. Menten, P. Morris, H. S. P. M¨uller, J. A. Murphy, D. A. Neufeld, V. Ossenkopf, J. C. Pearson, M. P´erault, T. G. Phillips, R. Plume, S.-L. Qin, P. Schilke, S. Schlemmer, J. Stutzki, N. Trappe, F. F. S. van der Tak, C. Vastel, H. W. Yorke, S. Yu, J. Zmuidzinas, A. Boogert, R. G¨usten, P. Hartogh, N. Honingh, A. Karpov, J. Kooi, J.-M. Krieg, R. Schieder, P. Hartogh, F. Helmich, P. Roelfsema, A. Tielens, B. Bumble, and J. H. Kawamura, 2010 A&A, Submitted. 7% of channels taken up by lines RMS of T A * 0.9 K Previous deep integration studies have reached 30 mK 2,3 2. Radhuber et al, in prep Sumner et al. in prep 3. B. Tercero, J. Cernicharo, J. R. Pardo, J. R. Goicoechea, A&A, Submitted

Submillimeter Spectrum 520 – 608 GHz ~900 lines with S/N>3 observed ~0.9 MHz line width ~100 kHz resolution

THz Spectrum THz ~450 lines with S/N>3 observed ~1.5 MHz linewidth ~100 kHz resolution

Experimental Setup Double-pass direct absorption spectrometer with frequency modulation GHz microwave synthesizer with Schottky diode multiplier source Si bolometer detector Source Si Bolometer Detector 3 m Quartz Cell Rooftop Reflector Polarizer

Results Microwave RMS: MHz 1126 new ground vibrational state lines assigned NewPreviousChange% Change A B C ΔJΔJ Δ JK ΔKΔK δJδJ δKδK ΦJΦJ ΦKΦK Φ KJ ΦJΦJ φJφJ φ JK φKφK

Analysis Δν = 2.06 MHz Experimental Predicted 33 31, 2 – 32 30, 3

Analysis cont’d… Δν = 2.25 MHz Experimental Predicted 37 29, 8 – 36 28, 9

Excited Vibrational State Δν = MHz Experimental Predicted v = , 1 – 31 30, 2

Improvements An improvement of 1.8 MHz! Experimental Previous Prediction New Prediction 33 31, 2 – 32 30, 3

Future Work Identification of Glycolaldehyde at high frequency in collaboration with the HIFI HEXOS team Assignment of v = 1, 2, 3 Acquisition of spectra of other molecules of interest at high frequency

Acknowledgements Widicus Weaver Group, Emory JPL Molecular Spectroscopy Lab Geoff Blake, Caltech