METHOD DEVELOPMENT FOR GAS-PHASE STUDY OF INTERSTELLAR ICE ANALOGUES AJ Mesko, Ian Wagner, Houston Smith, Stefanie Milam, Susanna Widicus Weaver

MOTIVATION FOR MILLIMETER/SUB- MILLIMETER STUDY OF ICY GRAIN CHEMISTRY A Leading theory for formation of Complex Organic Molecules (COMs) in the Interstellar Medium (ISM) Prebiotic Molecules Benefits of mm/sub-mm Highly Sensitive and Excellent Resolution Readily Comparable to mm/sub-mm astronomical data

Burke, Daren J.; Brown, Wendy A. Ice in space: surface science investigations of the thermal desorption of model interstellar ices on dust grain analogue surfaces. 2011, PCCP

REACTIONS INVOLVING ICY GRAINS H 2 O + hυ . OH + H  H 2 + O CH 3 OH + hυ . CH 3 +. OH  CH 3 O. + H . CH 2 OH + H Proposed Glycine Mechanisms : NH 2 + CH 2  NH 2 CH 2 + CO  TS  NH 2 CH 2 CO + OH  NH 2 CH 2 COOH CH 2 + CO  CH 2 CO + OH  CH 2 COOH +NH 2  NH 2 CH 2 COOH Amresh Singh, Alka Misra, and Poonam Tandon. Quantum chemical analysis for the formation of glycine in thew interstellar medium. Research in Astronomy and Astrophysics, 13(8):912, 2013.

INSTRUMENT CONSTRUCTION Proof-Of-Concept Instrument Constructed mostly from borrowed parts ~$4000 Key Components Agilent Technologies Analog Signal Generator VDI Multiplier Chain x3 – x27 frequency multiplication Detectors VDI Zero Bias Detector QMC Bolometer Lakeshore Temperature Controller Liquid Helium Cryostat Opthos Lyman- Source

mm/sub- mm source Detector Cold Gold Substrate UV Radiation UV Lamp H2OH2O CH 3 OH. OH. CH 3 O H2OH2O H2OH2O H2OH2O CH 3 OH Heating

EXPERIMENTS Room Temperature Photolysis of Methanol Temperature Programmed Desorption of Water and Methanol Ices Photodesorption of Water Ice

PHOTOLYSIS Gas Phase Methanol at T = 293 K

METHANOL LINES 9(1,1)  9(2,1) 10(2,0)  11(1,0) 10(1,0)  10(2,0) 6(0,0)  7(1,0)

FORMALDEHYDE LINES 6(0,6)  7(0,7) 6(4,3)  7(4,4) 6(2,5)  7(2,6) 6(3,3)  7(3,4)

TEMPERATURE PROGRAMMED DESORPTION Pure H 2 O Ice

1(0,0))  1(1,0)

PHOTODESORPTION Water Ice at T = 25K

FUTURE WORK AND CONCLUSIONS Methanol Photodesorption and Photolysis from Ice Surface Optimization of Scanning Routine More Complex Species Mixed Interstellar Ice Analogues More complex photoproducts Leading to detection of prebiotic molecules Addition of IR Spectroscopy Analysis of Ice-phase in tandem with Gas-phase Benchmarking Results have been gathered TPD of Pure Ices In good agreement with literature Gas Phase Photolysis Formaldehyde, product of methanol photolysis, has been detected Photodesorption of pure ices Water has been detected in the gas phase after UV irradiation of 25K ice

ACKNOWLEDGEMENTS Coauthors Dr. Susanna Widicus Weaver Dr. Stefanie Milam Mr. Ian Wagner Mr. Houston Smith Widicus Weaver Lab Group Dr. Nadine Wehres Brian Hays Luyao Zou NASA GSFC SIF Program Emory University Thom Orlando Group Georgia Tech