A Photoionization Reflectron Time‐of‐Flight Mass Spectrometric Study on the Detection of Ethynamine (HCCNH₂) and 2H‐Azirine (c‐H₂CCHN)

Abstract

Ices of acetylene (C2H2) and ammonia (NH3) were irradiated with energetic electrons to simulate interstellar ices processed by galactic cosmic rays in order to investigate the formation of C2H3N isomers. Supported by quantum chemical calculations, experiments detected product molecules as they sublime from the ices using photoionization reflectron time‐of‐flight mass spectrometry (PI‐ReTOF‐MS). Isotopically‐labeled ices confirmed the C2H3N assignments while photon energies of 8.81 eV, 9.80 eV, and 10.49 eV were utilized to discriminate isomers based on their known ionization energies. Results indicate the formation of ethynamine (HCCNH2) and 2H‐azirine (c‐H2CCHN) in the irradiated C2H2:NH3 ices, and the energetics of their formation mechanisms are discussed. These findings suggest that these two isomers can form in interstellar ices and, upon sublimation during the hot core phase, could be detected using radio astronomy.

Formation of Magnesium and Aluminum Oxides from Water and Metal Hydrides: Creation of the Smallest Ruby

“…The transition states and minima for four heavy atoms or larger are optimized with MP2/aug-cc-pVTZ, aug-cc-pV­(T+d)­Z for aluminum, but then have CCSD­(T)-F12b/cc-pVTZ-F12 single-point energies corrected with MP2/aug-cc-pVTZ ZPVEs. Such a procedure has demonstrated notable accuracy and clarification of the experiment for application to simulated laboratory astrochemistry for volatile species. , The reaction pathways are explored manually based on the motifs of H 2 dissociation established previously. − …”

“…Such a procedure has demonstrated notable accuracy and clarification of the experiment for application to simulated laboratory astrochemistry for volatile species. 57,58 The reaction pathways are explored manually based on the motifs of H 2 dissociation established previously. 31−33 ■ RESULTS AND DISCUSSION…”

A Search for Heterocycles in GOTHAM Observations of TMC-1

“…Crossed-beam experiments suggest the reaction of N­( 2 D) with ethylene (C 2 H 4 ) can form 2 H -azirine; however, isomerization to the more stable isomer acetonitrile (CH 3 CN) is expected, even under collision-free conditions . Recent work has shown the formation of 2 H -azirine in interstellar ice analogues of acetylene and ammonia after irradiation with energetic electrons . The suggested mechanism involves the reaction of imidogen (NH­(a 1 Δ)) with acetylene through addition to the carbon–carbon triple bond leading to 1 H -azirine, which may isomerize via a hydrogen shift to 2 H -azirine via a barrier of 108 kJ mol –1 .…”

“…81 Recent work has shown the formation of 2H-azirine in interstellar ice analogues of acetylene and ammonia after irradiation with energetic electrons. 82 The suggested mechanism involves the reaction of imidogen (NH(a 1 Δ)) with acetylene through addition to the carbon−carbon triple bond leading to 1Hazirine, which may isomerize via a hydrogen shift to 2H-azirine via a barrier of 108 kJ mol −1 .…”

A Search for Heterocycles in GOTHAM Observations of TMC-1

“…81 Recent work has shown the formation of 2Hazirine in interstellar ice analogues of acetylene and ammonia after irradiation with energetic electrons. 82 The suggested mechanism involves the reaction of imidogen (NH(a 1 ∆)) with acetylene through addition to the carboncarbon triple bond leading to 1H-azirine, which may isomerize via hydrogen shift to 2H-azirine via a barrier of 108 kJ mol −1 .…”