Millimeter and Submillimeter Studies of O( 1 D) Insertion Reactions to Form Molecules of Astrophysical Interest Brian Hays, Nadine Wehres, Bridget Alligood DePrince, Althea Roy, Jacob Laas, and Susanna L. Widicus Weaver Department of Chemistry Emory University
Star Formation in The Eagle Nebula
Unidentified Lines Physical Conditions, Molecular Abundances Abundance Predictions Molecules of Interest Transition Frequencies & Strengths Reaction Kinetics & Dynamics, Molecular Parameters Astrochemistry Research Laboratory Observations Modeling
Tracing Chemical Pathways in the ISM H 2 O + h OH + H H 2 + O CH 3 OH + h CH 3 + OH CH 3 O + H CH 2 OH + H NH 3 + h NH 2 + H H 2 CO + h HCO + H HCO + CH 2 OH HOCH 2 CHO(glycolaldehyde) HCO + CH 3 OCH 3 OCHO(methyl formate) HCO + OHHCOOH(formic acid) HCO + CH 3 CH 3 CHO(acetaldehyde) HCO + NH 2 H 2 NCHO(formamide) CH 3 + CH 3 OCH 3 OCH 3 (dimethyl ether) CH 3 + NH 2 CH 3 NH 2 (methyl amine) CH 3 + CH 2 OH CH 3 CH 2 OH(ethanol) CH 2 OH + CH 2 OHHOCH 2 CH 2 OH(ethylene glycol) h H 2 O, CO, CH 3 OH, NH 3, H 2 CO Ice mantle Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008 Laas, Garrod, Herbst, & Widicus Weaver, ApJ 728, 2011 Garrod & Widicus Weaver, Chemical Reviews, 2013
Prebiotic Molecule Formation
O( 1 D) Insertion Reactions
Gas-Phase O( 1 D) Insertion Reactions Microwave Synthesizer Millimeter/Submillimeter Frequency Multiplier Detector Excimer Laser Pulsed Valve + Fused Silica Capillary O 3 + hν (248 nm) O 2 ( 1 Δ) + O( 1 D) O( 1 D) + Precursor Product Oscilloscope Supersonic Expansion Hays et al. Chem. Phys. Lett. 2015
O 3 + hν (248 nm) O 2 ( 1 Δ) + O( 1 D) Ozone Depletion Ozone Depletion from Photolysis Hays et al. Chem. Phys. Lett. 2015
O( 1 D) + CH 4 CH 3 OH Ozone Depletion Proof of Concept: Methanol Production Hays et al. Chem. Phys. Lett. 2015
Ozone Depletion Methanol Produced via O( 1 D) Insertion Hays et al. Chem. Phys. Lett First detection of O( 1 D) insertion products in a supersonic expansion Also detected: H 2 CO, HO 2, CH 3 O, O 2 ( 1 Δ), H 2 O, HOOH, CO 3 0,3 – 2 0,2 3 0,3 + – 2 0, ,1 – 1 -1,1 4 0,4 + – 3 0,3 +
Next Target: Vinyl Alcohol Two vinyl alcohol conformers exist: syn-vinyl alcoholanti-vinyl alcohol Tautomerizes to acetaldehyde: Previous microwave studies by Saito (1976), Rodler & Bauder (1984) J max = 25, max = 120 GHz Detected in Sgr B2(N) by Apponi and Turner (2001)
New Mixing Source Gases are mixed immediately before the photolysis region Dark reactions between precursor gases are minimized Valves are more stable because side products cannot form in gas line O3O3 CH 2
Ozone Depletion Vinyl Alcohol Spectroscopy Hays et al. Chem. Phys. Lett Frequency coverage up to 450 GHz 49 new syn-vinyl alcohol lines detected Additional products observed: CO, O 2 ( 1 Δ), H 2 O, H 2 CO, HO 2, HOOH, CH 3 OH, CH 3 O, CH 3 CH 2 OH, CH 2 CO, CH 3 CHO, anti-vinyl alcohol
Ozone Depletion Vinyl Alcohol Spectroscopy Hays et al. Chem. Phys. Lett. 2015
O( 1 D) Insertion Reactions
Methylamine Reaction Hays & Widicus Weaver 2013, JPCA, 117, 7142 CCSD(T)//MP2/aug-cc-pVTZ Formation of Aminomethanol
CH 3 NH 2 + O( 1 D) → HOCH 2 NH 2 (aminomethanol) CH 3 NHOH (n-methyl hydroxylamine) CH 3 ONH 2 (aminomethyl ether) Methylamine + O( 1 D) Insertion Reactions Known molecules that have been detected: O 2 ( 1 Δ), NO, NO 2, HCN, HNC, HNO, HO 2, NO 2, H 2 CO, H 2 O 2, H 2 CN, HNCO, HCNO, CH 3 O, CH 2 NH, CH 3 OH, NH 2 CHO Methylenimine CH 2 NH J Ka,Kc = 1 1,0 – 1 0,1 F=0–1 2–1 1–2 F=2–2 1–0 1–1
CH 3 NH 2 + O( 1 D) → HOCH 2 NH 2 Detection of Aminomethanol (?) Spectral carrier is likely aminomethanol: Hyperfine splitting indicates an N-containing molecule Frequencies match with prediction from ZPE-corrected calculations Frequencies do not match for other N-containing products
Observational Line Surveys
Acknowledgements The Widicus Weaver Group: Brian Hays, Houston Smith, Samuel Zinga, Luyao Zou, Morgan McCabe, AJ Mesko Former group members: Nadine Wehres, Jacob Laas, Anthony Chirillo, Mateo Correa, Jim Sanders, Trevor Cross, Althea Roy, Bridget Alligood DePrince, Mary Radhuber, Danna Qasim, Blithe Rocher, Shiya Wang, Jessica Walsh O’Sullivan, Brandon Carroll, Anne Carroll, Jay Kroll, Brett McGuire, Sophie Lang, Thomas Anderson NASA Herschel OT1 Analysis Program RSA No NASA APRA Grant NNX11AI07G NSF CAREER Award CHE NSF Center for Chemical Innovation CHE Michael Heaven & Joel Bowman, Emory Eric Herbst & Brooks Pate, UVA Steven Shipman, New College of Florida CSO/Caltech: Darek Lis, Matthew Sumner, Geoff Blake, Frank Rice, Jonas Zmuidzinas, & Thomas Phillips
Ozone Depletion Collisional Stabilization of Products Hays et al. Chem. Phys. Lett. 2015