An Experimental Investigation of the Synthesis of Complex Organic Molecules in Interstellar Analog Ices

The overarching activity of this project is to explore experimentally in a state-of-the-art ultra-high vacuum surface science machine the formation of key classes of complex organic molecules (COMs) – per astronomical definition organic molecules containing atoms of carbon, hydrogen, oxygen, and nitrogen – upon exposure of interstellar ice analog samples to Lyman α photons and to define the level of molecular complexity that can ultimately be reached in the interstellar medium (ISM). These key classes are aldehydes (HCOR), ketones (RCOR’), carboxylic acids (RCOOH), esters (RCOOR’), and (functionalized) amides (RCONH₂). Those objectives are accomplished by systematically simulating the conditions of ice-coated interstellar grains as prevalent in cold molecular clouds and high- and low-mass star forming regions in a next-generation ultra-high vacuum surface science setup by exposing interstellar ice analog samples resembling ices in cold molecular clouds as well as in low- and high-mass star forming regions at astrophysically relevant temperatures (10–50 K) to Lyman α photons (10.2 eV). We pursue a transformative methodology by unraveling the formation of COMs on line and in situ via complementary detection schemes in the condensed phase (Infrared, Raman, UV-VIS) and upon sublimation into the gas phase via fragment-free, single photon vacuum ultraviolet (VUV) photoionization (PI) linked with a reflectron time of flight mass spectroscopy (PI/REMPI-ReTOF-MS) connected to a space simulation chamber. This unique equipment permits elucidating transformative concepts on the formation of COMs in interstellar ices upon exposure to Lyman α photons exploiting innovative technology to detect COMs through the implementation of modern photoionization techniques.

nsfast_1 — Key classes of COMs detected in the ISM suggested to be formed on ice-coated interstellar grains. Molecules in bold were also detected in comet 67P/Churyumov–Gerasimenko.

nsf_nasa — Critical effect of non-equilibrium chemical reactions on the formation of complex organic molecules within interstellar ices. Solely gas phase reactions cannot reproduce the observed fractional abundances. The astrochemical models were carried out by the group of Prof. Eric Herbst (University of Virginia).

An understanding of the formation of key classes of COMs is of core value to the laboratory astrophysics, astrochemistry, and astronomy communities. Firstly, our project advances the knowledge of the fundamental processes yielding COMs on ice-coated interstellar grains in cold molecular clouds and in star forming regions. Since the transition from a molecular cloud to star forming regions critically depends on the molecular inventory, it is vital to elucidate the processes of how COMs are formed in these environments. This also assists testing chemical models of molecular clouds and of star forming regions as these molecules play a key role in astrobiology and their synthetic pathways are constrained by physical (radiation, temperature) and chemical (ice composition) conditions. Secondly, structural isomers – molecules with the same molecular formula but different connectivities of atoms – serve as a molecular ‘clock’ and ‘tracers’ in elucidating the evolutionary stage of cold molecular clouds and star forming regions. The absence of data on products, branching ratios, and rate constants of their formation and their dependence on the ice temperature and composition limits the perception how COMs are formed. Our project provides this information and provides transformative concepts on the formation of COMs on interstellar grains and defines an inventory of COMs thus constraining the level of molecular complexity that can ultimately be achieved in space. Also, if a COM, which has not been detected in the ISM so far, will be identified in the present experiments, astronomical searches of this molecule in the gas phase of the ISM might be prompted. Finally, since COMs have also been identified in the Murchison meteorite, our project aims to bring us closer to better understand which key classes of COMs might have been produced exogenously in the ISM, (partly) incorporated into parent bodies of, e.g., Murchison, and then delivered to early Earth.

nsfast_4 — Left: Benefits of fragment free single photon ionization. a): electron impact ionization (70 eV) fragmentation pattern of methyl formate (HCOOCH₃). Note extensive fragmentation of the parent peak at m/z = 60 following electron impact; b) single photon fragment free ionization (10.9 eV) resulting in an intense molecular ion. Right: Sublimation profile of the molecular ion C₃H₆O⁺ (m/z = 58) after photoionization of the subliming molecules with 10.49 eV (a) and 9.92 eV (b) in irradiated carbon dioxide – propylene ices; the fits of the 9.92 eV experiment were subtracted from the 10.49 eV experiment (c); the result corresponds to signal from propylene oxide (c-C₃H₆O) (c). At a photon energy of 10.49 eV, *all* C₃H₆O isomers are ionized; at 9.92 eV, C₃H₆O isomers except propylene oxide are ionized.

nsfast_5 — Left: Benefits of fragment free single photon ionization. a): electron impact ionization (70 eV) fragmentation pattern of methyl formate (HCOOCH₃). Note extensive fragmentation of the parent peak at m/z = 60 following electron impact; b) single photon fragment free ionization (10.9 eV) resulting in an intense molecular ion. Right: Sublimation profile of the molecular ion C₃H₆O⁺ (m/z = 58) after photoionization of the subliming molecules with 10.49 eV (a) and 9.92 eV (b) in irradiated carbon dioxide – propylene ices; the fits of the 9.92 eV experiment were subtracted from the 10.49 eV experiment (c); the result corresponds to signal from propylene oxide (c-C₃H₆O) (c). At a photon energy of 10.49 eV, *all* C₃H₆O isomers are ionized; at 9.92 eV, C₃H₆O isomers except propylene oxide are ionized.

nsfast_6 — Top view of the main chamber including the cryogenic target (point of converging lines), analytical instruments, and photolysis source. The source is aligned with respect to the target to allow for the simultaneous in situ monitoring of IR, Ra, and UV-VIS spectroscopies. The inset shows the geometry of the ReTOF lenses with respect to the target and ionization laser.

nsfast_7 — Overview of W.M. Keck Research Laboratory in Astrochemistry

Recent Selected Publications

1. R.I. Kaiser, S. Maity, B.M. Jones, Synthesis of Prebiotic Glycerol in Interstellar Ices, Angew. Chem. Int. Ed., 54, 195-200 (2015). (PDF)

2. S. Maity, R.I. Kaiser, and B.M. Jones, Formation of complex organic molecules in methanol and methanol-carbon monoxide ice exposed to ionizing radiation - a combined FTIR and reflectron time-of-flight mass spectrometry study, Phys. Chem. Chem. Phys., 17, 3081 - 3114 (2015). (PDF)

3. M.J. Abplanalp, A. Borsuk, B.M. Jones, R.I. Kaiser, On the Formation and Isomer Specific Detection of Propenal (C₂H₃CHO) and Cyclpropanone (c-C₃H₄O) in Interstellar Model Ices-A Combined FTIR and Reflectron Time-of-Flight Mass Spectroscopic Study, Ap. J., 814, 45 (2015). (PDF)

4. M.J. Abplanalp, M. Förstel, and R.I. Kaiser, Exploiting single photon vacuum ultraviolet photoionization to unravel the synthesis of complex organic molecules in interstellar ices, Chemical Physics Letters, 644, 79-98 (2016). (PDF)

5. M. Förstel, P. Maksyutenko, B.M. Jones, B-J Sun, A.H.H. Chang, R. I. Kaiser, Synthesis of urea in cometary model ices and implications for Comet 67P/Churyumov-Gerasimenko, Chem. Comm. 52, 741-744 (2016). (PDF)

6. M. Förstel, P. Maksyutenko, A.M. Mebel, R.I. Kaiser, Pentacarbon dioxide (C₅O₂) formation and its role as a tracer of solar system evolution, Ap. J. L. 818:L30, 1-6 (2016). (PDF)

7. M. Förstel, P. Maksyutenko, B.M. Jones, B-J Sun, H.C. Lee, A.H.H. Chang, R.I. Kaiser, On the Formation of Amide Polymers via Carbonyl-Amino Group Linkages in Energetically Processed Ices of Apical Relevance, Ap. J. 820, 117 (2016). (PDF)

8. B.M. McMurtry, A.M. Turner, S.E.J. Saito, R.I. Kaiser, On the formation of Niacin (Vitamin B3) and Pyridine Carboxylic Acids in Interstellar Model Ices, Chemical Physics 472, 173 (2016). (PDF)

9. M.J. Abplanalp, S. Gozem, A.I. Krylov, C.N. Shingledecker, E. Herbst, R.I. Kaiser, A study of interstellar aldehydes and enols as tracers of a cosmic ray-driven nonequilibrium synthesis of complex organic molecules, Proceedings of the National Acadamy of Sciences 113, 7727-7732 (2016). (PDF)

10. M.J. Abplanalp, R. I. Kaiser, Complex hydrocarbon chemistry in interstellar and solar system ices revealed: a combined infrared spectroscopy and reflectron time-of-flight mass spectrometry analysis of ethane (C₂H₆) and D6-ethane (C₂D₆) ices exposed to ionizing radiation, Ap. J., 827, 132 (2016). (PDF)

11. B.M. McMurtry, S.E.J. Saito, A.M. Turner, H.K. Chakravarty, R.I. Kaiser, On the Formation of Benzoic Acid and Higher-Order Benzene Carboxylic Acids in Interstellar Model Ice Grains, Ap. J., 831, 174 (2016). (PDF)

12. A. Bergantini, R.I. Kaiser. In Situ Detection of Organics in the Comet 67P/Churyumov-Gerasimenko, Chem 1(6), 822-829 (2016). (PDF)

13. M.J. Abplanalp, R.I. Kaiser, Implications for Extraterrestrial Hydrocarbon Chemistry: Analysis of Ethylene (C₂H₄) and D4-Ethylene (C₂D₄) Ices Exposed to Ionizing Radiation via Combined Infrared Spectroscopy and Reflectron Time-of-flight Mass Spectrometry, J. ApJ, 836, 195 (2017). (PDF)

14. A. Bergantini, Pavlo Maksyutenko, R.I. Kaiser, On the Formation of the C₂H₆O Isomers Ethanol (C₂H₅OH) and Dimethyl Ether (CH₃OCH₃) in Star-forming Regions, Ap. J., 841:96, 1-24 (2017). (PDF)

15. M. Förstel, A. Bergantini, P. Maksyutenko, S. Góbi, R.I. Kaiser, Formation of Methylamine and Ethylamine in Extraterrestrial Ices and Their Role as Fundamental Building Blocks of Proteinogenic α-amino Acids, Ap. J., 845, 83 (2017). (PDF)

16. M.J. Abplanalp, B.M. Jones, R.I. Kaiser, Untangling the methane chemistry in interstellar and solar system ices toward ionizing radiation: a combined infrared and reflectron time-of-flight analysis, Phys. Chem. Chem. Phys., 20, 5435-5468 (2018). (PDF)

17. Y.A. Tsegaw, S. Góbi, M. Förstel, P. Maksyutenko, W. Sander, R.I. Kaiser, Formation of Hydroxylamine in Low-Temperature Interstellar Model Ices, J. Phys. Chem. A, 121, 7477-7493 (2017). (PDF)

18. A. Bergantini, S. Góbi, M.J. Abplanalp, R.I. Kaiser, A Mechanistical Study on the Formation of Dimethyl Ether (CH₃OCH₃) and Ethanol (CH₃CH₂OH) in Methanol-containing Ices and Implications for the Chemistry of Star-forming Regions, ApJ, 852, 70 (2018). (PDF)

19. C. Zhu, A. M. Turner, M. J. Abplanalp, R. I. Kaiser, Formation of High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO₂) and Methane(CH₄), ApJS, 234, 15 (2018). (PDF)

20. M.J. Abplanalp, S. Góbi, A.Bergantini, A.M. Turner, R.I. Kaiser, On the Synthesis of Chocolate Flavonoids (Propanols, Butanals) in the Interstellar Medium, Chem. Phys. Chem. 19, 556-560 (2018). (PDF)

21. A. Bergantini, R. Frigge, R.I. Kaiser Constraining the Molecular Complexity in the Interstellar Medium-The Formation of Ethyl Methyl Ether (CH₃OCH₂CH₃) in Star-forming Regions, The Astrophysical Journal 859, 59 (2018). (PDF)

22. A. Bergantini, M.J. Abplanalp, P. Pokhilko, A.I. Krylov, C.N. Shingledecker, E. Herbst, R.I. Kaiser, A Combined Experimental and Theoretical Study on the Formation of Interstellar Propylene Oxide (CH₃CHCH₂O)-A Chiral Molecule, The Astrophysical Journal 860, 108 (2018). (PDF)

23. R. Frigge, C. Zhu, A. M. Turner, M. J. Abplanalp, A. Bergantini, B-J Sun, Y-L Chen, A. H. H. Chang, R. I. Kaiser, A Vacuum Ultraviolet Photoionization Study on the Formation of N-methyl Formamide (HCONHCH₃) in Deep Space: A Potential Interstellar Molecule with a Peptide Bond, The Astrophysical Journal 862, 84 (2018). (PDF)

24. A. Bergantini, C. Zhu, R. I. Kaiser, A Photoionization Reflectron Time-of-flight Mass Spectrometric Study on the Formation of Acetic Acid (CH₃COOH) in Interstellar Analog Ices, The Astrophysical Journal 862, 140 (2018). (PDF)

25. C. Zhu, R. Frigge, A. M. Turner, M. J. Abplanalp, B.-J. Sun, Y.-L. Chen, A. H. H. Chang, R. I. Kaiser, A vacuum ultraviolet photoionization study on the formation of methanimine (CH₂NH) and ethylenediamine (NH₂CH₂CH₂NH₂) in low temperature interstellar model ices exposed to ionizing radiation, Phys. Chem. Chem. Phys. 21, 1952-1962, (2019). (PDF)

26. M.J. Abplanalp, S. Góbi, R.I. Kaiser, On the Formation and the Isomer Specific Detection of Methylacetylene (CH₃CCH), Propene (CH₃CHCH₂), Cyclopropane (c-C₃H₆), Vinylacetylene (CH₂CHCCH), and 1,3-Butadiene (CH₂CHCHCH₂) from Interstellar Methane Ice Analogues, Phys. Chem. Chem. Phys. 21, 5378-5393, (2019). (PDF) (Supplemental Information)

27. A. Eckhardt, A. Bergantini, S. Singh, P.R. Schreiner & R.I. Kaiser Formation of Glyoxylic Acid in Interstellar Ices: A Key Entry Point for Prebiotic Chemistry, Angewandte Chemie Int. Ed. 58, 17, 5663-5667, (2019). (PDF) (Supplemental Information)

28. M. J. Aplanalp, R.I. Kaiser, On the formation of complex organic molecules in the interstellar medium: untangling the chemical complexity of carbon monoxide-hydrocarbon containing ice analogues exposed to ionizing radiation via a combined infrared and reflectron time-of-flight analysis, Phys. Chem. Chem. Phys., 21, 16949-16980 (2019). (PDF) (Supplemental Information)

29. C. Zhu, R. Frigge, A. Bergantini, R. C. Fortenberry, R. I. Kaiser Untangling the Formation of Methoxymethanol (CH₃OCH₂OH) and Dimethyl Peroxide (CH₃OOCH₃) in Star-forming Regions, The Astrophysical Journal, 881, 156 (2019). (PDF)

30. M. J. Abplanalp, R. Frigge, R. I. Kaiser, Low-temperature synthesis of polycyclic aromatic hydrocarbons in Titan's surface ices and on airless bodies, Science Advances, 5, eaaw5841 (2019). (PDF) (Supplemental Information) )

31. M. J. Abplanalp, R. I. Kaiser, Implications for Extraterrestrial Hydrocarbon Chemistry: Analysis of acetylene (C₂H₂) and D2-acetylene (C₂D₂) Ices Exposed to Ionizing Radiation via Ultraviolet-Visible Spectroscopy, Infrared Spectroscopy, and Reflectron Time-of-flight Mass Spectrometry, Astrophy. J. 889, 3 (2020). (PDF)

32. C. Zhu, A. M. Turner, C. Meinert, R. I. Kaiser, On the Production of Polyols and Hydroxycarboxylic Acids in Interstellar Analogous Ices of Methanol, Astrophy. J. 889, 134 (2020). (PDF)

33. A. M. Turner, A. Koutsogiannis, N. F. Kleimeier, A. Bergantini, C. Zhu, R. C. Fortenberry, R. I. Kaiser, An Experimental and Theoretical Investigation into the Formation of Ketene and Ethynol (HCCOH) in Interstellar Analog Ices, Astrophys. J., 896, 88, (2020). (PDF)

34. N. F. Kleimeier, A. M. Turner, R. C. Fortenberry, R. I. Kaiser, On the Formation of the Popcorn Flavorant 2,3-Butanedione (CH₃COCOCH₃) in Acetaldehyde-Containing Interstellar Ices, ChemPhysChem 21, 1531– 1540 (2020). (PDF) (Supplemental Information)

35. N. F. Kleimeier, A. K. Eckhardt, R. I. Kaiser, A Mechanistic Study on the Formation of Acetic Acid (CH₃COOH) in Polar Interstellar Analog Ices Exploiting Photoionization Reflectron Time–of–flight Mass Spectrometry , Astrophys. J., 901, 84 (2020). (PDF)

36. N. F. Kleimeier, A. K. Eckhardt, P. R. Schreiner, R. I. Kaiser, Interstellar Formation of Biorelevant Pyruvic Acid (CH₃COCOOH), Chem, 6, 1-11 (2020). (PDF) (Supplemental Information)

37. A. M. Turner, R. I. Kaiser, Exploiting Photoionization Reflectron Time-of-Flight Mass Spectrometry to Explore Molecular Mass Growth Processes to Complex Organic Molecules in Interstellar and Solar System Ice Analogs , Acc. Chem. Res., 53, 2791-2805 (2020). (PDF) (Figure Files)

38. N. F. Kleimeier, M. J. Abplanalp, R. N. Johnson, S. Gozem , J. Wandishin, C. N. Shingledecker, R. I. Kaiser Cyclopropenone (c-C₃H₂O) as a Tracer of the Nonequilibrium Chemistry Mediated by Galactic Cosmic Rays in Interstellar Ices, Astrophys. J., 911, 24 (2021). (PDF)

39. A. M. Turner, S. Chandra, R. C. Fortenberry, R. I. Kaiser, A Photoionization Reflectron Time-of-Flight Mass Spectrometric Study on the Detection of Ethynamine (HCCNH₂) and 2H-Azirine (c-H₂CCHN), ChemPhysChem, 22, 985-994 (2021). (PDF) (Supplemental Information)

40. N. F. Kleimeier, R. I. Kaiser, Interstellar Enolization-Acetaldehyde (CH₃CHO) and Vinyl Alcohol (H₂CCH(OH)) as a Case Study, ChemPhysChem, 22, 1229– 1236 (2021). (PDF) (Supplemental Information)

41. A. M. Turner, A. Bergantini, A. S. Koutsogiannis, N. F. Kleimeier, S. K. Singh, C. Zhu, A. K. Eckhardt, R. I. Kaiser, A Photoionization Mass Spectrometry Investigation into Complex Organic Molecules Formed in Interstellar Analog Ices of Carbon Monoxide and Water Exposed to Ionizing Radiation, Astrophys. J., 916, 24 (2021). (PDF)

42. N. F. Kleimeier, A. K. Eckhardt, R. I. Kaiser, Identification of Glycolaldehyde Enol (HOHC═CHOH) in Interstellar Analogue Ices, JACS, 143, 14009-14018 (2021). (PDF) (Supplemental Information)

43. C. Zhu, A. K. Eckhardt, S. Chandra, A. M. Turner, P. R. Schreiner, R. I. Kaiser, Identification of A Prismatic P₃N₃ Molecule Formed from Electron Irradiated Phosphine-nitrogen Ices, Nat. Commun., 12, 5467 (2021). (PDF) (Supplemental Information)

44. C. Zhu, A. Bergantini, S. K. Singh, M. J. Abplanalp, R. I. Kaiser, Rapid Radical–Radical Induced Explosive Desorption of Ice-coated Interstellar Nanoparticles, Astrophys. J., 920, 73 (2021). (PDF)

45. C. Zhu, N. F. Kleimeier, A. M. Turner, S. K. Singh, R. C. Fortenberry, R. I. Kaiser, Synthesis of methanediol [CH₂(OH)₂]: The simplest geminal diol, Proc. Natl. Acad. Sci. U.S.A., 119, e2111938119 (2022). (PDF) (Supplemental Information)

46. N. F. Kleimeier, R. I. Kaiser, Bottom-Up Synthesis of 1,1-Ethenediol (H₂CC(OH)₂) - the Simplest Unsaturated Geminal Diol - in Interstellar Analogue Ices, J. Phys. Chem. Lett., 24, 229-235 (2022). (PDF) (Supplemental Information)

47. N. F. Kleimeier, Y. Liu, A. M. Turner, L. A. Young, C. H. Chin, T. Yang, X. He., J. I. Lo, B. M. Cheng, R. I. Kaiser, Excited state photochemically driven surface formation of benzene from acetylene ices on Pluto and in the outer solar system, Phys. Chem. Chem. Phys., 24, 1424-1436 (2022). (PDF) (Supplemental Information)

48. S. K. Singh, C. Zhu, J. L. Jeunesse, R. C. Fortenberry, R. I. Kaiser, Experimental Identification of Aminomethanol (NH₂CH₂OH) – The Key Intermediate in the Strecker Synthesis, Nat. Commun. 13, 375 (2022). (PDF) (Supplemental Information)

49. C. Zhang, C. Zhu, A. K. Eckhardt, R. I. Kaiser, Detection of 1H-Triphosphirene (c-HP₃) and 2-Triphosphenylidene (HP₃): The Isovalent Counterparts of 1H-Triazirine (c-HN₃) and Hydrazoic Acid (HN₃). J. Phys. Chem. Lett., 13, 2725-2730 (2022). (PDF) (Supplemental Information)

50. J. Wang, N. F. Kleimeier, R. N. Johnson, S. Gozem, M. J. Abplanalp, A. M. Turner, J. H. Marks, R. I. Kaiser, Photochemically triggered cheletropic formation of cyclopropenone (c-C₃H₂O) from carbon monoxide and electronically excited acetylene, Phys. Chem. Chem. Phys., 24, 17449–17461 (2022). (PDF) (Supplemental Information) (Data Files)

51. C. Zhang, C. Zhu, A. K. Eckhardt, R. I. Kaiser, Formation of the elusive tetrahedral P₃N molecule, Sci. Adv., 8, eabo5792 (2022). (PDF) (Supplemental Information)

52. C. Zhu, H. Wang, I. Medvedkov, J. Marks, M. Xu, J. Yang, T. Yang, Y. Pan, R. I. Kaiser, Exploitation of Synchrotron Radiation Photoionization Mass Spectrometry in the Analysis of Complex Organics in Interstellar Model Ices, J. Phys. Chem. Lett., 13, 6875-6882 (2022). (PDF) (Supplemental Information)

53. R. C. Fortenberry, R. J. McMahon, R. I. Kaiser, 10 Years of the ACS PHYS Astrochemistry Subdivision, J. Phys. Chem. A, 126, 6571-6574 (2022). (PDF)

54. J. H. Marks, J. Wang, R. C. Fortenberry, R. I. Kaiser, Preparation of methanediamine (CH₂(NH₂)₂) - A precursor to nucleobases in the interstellar medium, Proc. Nat. Acad. Sci. U.S.A., 119, e2217329119 (2022). (PDF) (Supplemental Information) (Data Files)

55. S. K. Singh, N. F. Kleimeier, A. K. Eckhardt, R. I. Kaiser, A Mechanistic Study on the Formation of Acetone (CH₃COCH₃), Propanal (CH₃CH₂CHO), Propylene Oxide (c-CH₃CHOCH₂) along with Their Propenol Enols (CH₃CHCHOH/CH₃C(OH)CH₂) in Interstellar Analog Ices, Astrophys. J., 941, 103 (2022). (PDF)

56. J. Wang, J. H. Marks, L. B. Tuli, A. M. Mebel, V. N. Azyazov, R. I. Kaiser, Formation of Thioformic Acid (HCOSH) – The Simplest Thioacid – in Interstellar Ice Analogues, J. Phys. Chem. A, 126, 9699−9708 (2022). (PDF) (Supplemental Information)

57. J. Wang, J. H. Marks, A. M. Turner, A. A. Nikolayev, V. N. Azyazov, A. M. Mebel, R. I. Kaiser, Mechanistical study on the formation of hydroxyacetone (CH₃COCH₂OH), methyl acetate (CH₃COOCH₃), and 3-hydroxypropanal (HCOCH₂CH₂OH) along with their enol tautomers (prop-1-ene-1,2-diol (CH₃C(OH)CHOH), prop-2-ene-1,2-diol (CH₂C(OH)CH₂OH),1-methoxyethen-1-ol (CH₃OC(OH)CH₂) and prop-1-ene-1,3-diol (HOCH₂CHCHOH)) in interstellar ice analogs, Phys. Chem. Chem. Phys., 25, 936-953 (2023). (PDF) (Supplemental Information) (Data Files)

58. J. H. Marks, J. Wang, M. M. Evseev, O. V. Kuznetsov, I. O. Antonov, R. I. Kaiser, Complex Reactive Acids from Methanol and Carbon Dioxide Ice: Glycolic Acid (HOCH₂COOH) and Carbonic Acid Monomethyl Ester (CH₃OCOOH), Astrophys. J., 942, 43 (2023). (PDF) (Data Files)

59. C. Zhang, A. M. Turner, J. Wang, J. H. Marks, R. C. Fortenberry, R. I. Kaiser, Low-Temperature Thermal Formation of the Cyclic Methylphosphonic Acid Trimer [c-(CH₃PO₂)₃], ChemPhysChem 24, e202200660 (2023). (PDF) (Supplemental Information) (Data Files)

60. J. H. Marks, J. Wang, N. F Kleimeier, A. M. Turner, A. K. Eckhardt, R. I. Kaiser, Prebiotic Synthesis and Isomerization in Interstellar Analog Ice: Glycinal, Acetamide, and Their Enol Tautomers, Angew. Chem. Int. Ed. 62, e202218645 (2023). (PDF) (Supplemental Information) (Data Files)

61. J. Wang, J. H. Marks, A. M. Turner, A. M. Mebel, A. K. Eckhardt, R. I. Kaiser, Gas-phase detection of oxirene, Sci. Adv., 9, eadg1134 (2023). (PDF) (Supplemental Information) (Data Files)

62. J. Wang, A. A. Nikolayev, J. H. Marks, M. Mcanally, V. N. Azyazov, A. K. Eckhardt, A. M. Mebel, R. I. Kaiser, Quantum Tunneling Mediated Low-Temperature Synthesis of Interstellar Hemiacetals, J. Phys. Chem. Lett., 14, 6078−6085 (2023). (PDF) (Supplemental Information) (Data Files)

63. J. Wang, A. A. Nikolayev, C. Zhang, J. H. Marks, V. N. Azyazov, A. K. Eckhardt, A. M. Mebel, R. I. Kaiser, Synthesis of interstellar propen-2-ol (CH₃C(OH)CH₂) – the simplest enol tautomer of a ketone, Phys. Chem. Chem. Phys., 25, 17460 (2023). (PDF) (Supplemental Information) (Data Files)

64. C. Zhang, J. Wang, A. M. Turner, J. H. Marks, S. Chandra, R. C. Fortenberry, R. I. Kaiser, On the Formation of Vinylamine (C₂H₃NH₂) in Interstellar Ice Analogs , Astrophys. J., 952, 132 (2023). (PDF) (Supplemental Information) (Data Files)

65. J. Marks, A. A. Nikolayev, M. M. Evseev, J. Wang, A. M. Turner, N. F. Kleimeier, O. V. Kuznetsov, M. McAnally, A. N. Morozov, I. O. Antonov, A. M. Mebel, R. I. Kaiser, Quantum-Tunneling-Mediated Synthesis of Prebiotic Chelation Agents in Interstellar Analog Ices, Chem, 9, 1-18 (2023). (PDF) (Supplemental Information) (Data Files)

66. J. H. Marks, J. Wang, B.-J. Sun, M. McAnally, A. M. Turner, A. H.-H. Chang, R. I. Kaiser, Thermal Synthesis of Carbamic Acid and Its Dimer in Interstellar Ices: A Reservoir of Interstellar Amino Acids, ACS Cent. Sci., 9, 2171-2368 (2023). (PDF) (Supplemental Information) (Data Files)

67. J. Wang, J. H. Marks, A. K. Eckhardt, R. I. Kaiser, Bottom-Up Formation of Antiaromatic Cyclobutadiene (c-C₄H₄) in Interstellar Ice Analogs, J. Phys. Chem. Lett., 15, 1211−1217 (2024). (PDF) (Supplemental Information) (Data Files)

68. J. Wang, J. H. Marks, R. C. Fortenberry, R. I. Kaiser, Interstellar formation of glyceric acid [HOCH₂CH(OH)COOH]—The simplest sugar acid, Sci. Adv., 10, eadl3236 (2024). (PDF) (Supplemental Information) (Data Files)