The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz Brandon Carroll 1 Brian...
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Transcript of The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz Brandon Carroll 1 Brian...
The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz
Brandon Carroll1
Brian Drouin2
Susanna Widicus Weaver1
June 22, 2010
2. 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
– 12-26 GHz, 49 lines assigned in the ground vibrational state– Lines from 3 excited vibrational states also assigned– Stark measurements of dipole moment
– μa = 0.12 D, μb = 2.73 D
• Millimeter-Wave Spectrum– Butler et al. (2001)2
, Widicus Weaver et al. (2005)3
– 128-354 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, 259
3. 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, 188-192, 2005.
2. 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, L107
2. D. T. Halfen , A. J. Apponi , N. Woolf , R. Polt , and L. M. Ziurys 2006, ApJ, 639:237-245
New Observatories
• Herschel Space Observatory– 480 GHz - 1.2 THz, 1.4 THz - 1.9 THz
• Atacama Large Millimeter Array (ALMA)– 80 GHz - 950 GHz
• Stratospheric Observatory for Infrared Astronomy (SOFIA)– 500 GHz - 2.1 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 TA* 0.9 K
• Previous deep integration studies have reached 30 mK2,3
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
Experimental Setup
• Double-pass direct absorption spectrometer with frequency modulation
• 1 - 20 GHz microwave synthesizer with Schottky diode multiplier source
• Si bolometer detector
Source
Si Bolometer Detector
3 m Quartz Cell
Rooftop ReflectorPolarizer
Results
Microwave RMS: 0.113416 MHz1126 new ground vibrational state lines assigned
New Previous Change % Change
A 18446.2610 18446.2607 0.0002828 0.00000
B 6525.9971 6525.9964 0.0006912 0.00001
C 4969.2354 4969.2358 -0.0003955 0.00001
ΔJ -0.0062214364 -0.0062223392 0.000000903 0.01451
ΔJK 0.0203923859 0.0203979775 -0.000005592 0.02741
ΔK -0.0477193370 -0.0477233754 0.000004038 0.00846
δJ -0.0018343918 -0.0018337838 -0.000000608 0.03316
δK -0.0088635544 -0.0088788916 0.000015337 0.17274
ΦJ -0.0000000071 -0.0000000065 -0.000000001 9.98546
ΦK 0.0000001691 0.0000001909 -0.000000022 11.39959
ΦKJ -0.0000008020 -0.0000007721 -0.000000030 3.87205
ΦJ 0.0000010552 0.0000010570 -0.000000002 0.17727
φJ -0.0000000022 -0.0000000025 0.000000000 12.54952
φJK -0.0000000262 -0.0000000130 -0.000000013 101.57545
φK 0.0000002995 0.0000001909 0.000000109 56.93560
Improvements
An improvement of 1.8 MHz!Experimental
Previous PredictionNew Prediction
3331, 2 – 3230, 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