The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz Brandon Carroll 1 Brian...

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The Submillimeter Absorption Spectrum of Glycolaldehyde from 500 GHz to 1THz Brandon Carroll 1 Brian Drouin 2 Susanna Widicus Weaver 1 June 22, 2010 2. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 1. Department of Chemistry, Emory University, Atlanta, GA 30322

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

THz Spectrum• 1.07-1.2 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

• 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

AnalysisΔν = 2.06 MHz

Experimental

Predicted

3331, 2 – 3230, 3

Analysis cont’d…

Δν = 2.25 MHzExperimental

Predicted

3729, 8 – 3628, 9

Excited Vibrational State

Δν = 11.16 MHz

Experimental

Predicted

v = 2

3231, 1 – 3130, 2

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

Acknowledgements

• Widicus Weaver Group, Emory

• JPL Molecular Spectroscopy Lab

• Geoff Blake, Caltech