Formation of the simplest amide in molecular clouds: formamide (NH$_{2}$CHO) and its derivatives in H$_2$O-rich and CO-rich interstellar ice analogs upon VUV irradiation

K. -J. Chuang; C. J\{"a}ger; S. A. Krasnokutski; D. Fulvio; Th. Henning

doi:10.3847/1538-4357/ac7320

paper

Formation of the simplest amide in molecular clouds: formamide (NH $_{2}$ CHO) and its derivatives in H $_{2}$ O-rich and CO-rich interstellar ice analogs upon VUV irradiation

arXiv:2206.10470 · doi:10.3847/1538-4357/ac7320

Abstract

The astronomical detection of formamide (NH $_{2}$ CHO) toward various star-forming regions and in cometary material implies that the simplest amide might have an early origin in dark molecular clouds at low temperatures. Laboratory studies have proven the efficient NH $_{2}$ CHO formation in interstellar CO:NH $_{3}$ ice analogs upon energetic processing. However, it is still under debate, whether the proposed radical-radical recombination reactions forming complex organic molecules remain valid in an abundant H $_{2}$ O environment. The aim of this work was to investigate the formation of NH $_{2}$ CHO in H $_{2}$ O- and CO-rich ices under conditions prevailing in molecular clouds. Therefore, different ice mixtures composed of H $_{2}$ O:CO:NH $_{3}$ (10:5:1), CO:NH $_{3}$ (4:1), and CO:NH $_{3}$ (0.6:1) were exposed to vacuum ultraviolet photons in an ultra-high vacuum chamber at 10 K. Fourier-transform infrared spectroscopy was utilized to monitor in situ the initial and newly formed species as a function of photon fluence. The infrared spectral identifications are complementarily secured by a temperature-programmed desorption experiment combined with a quadrupole mass spectrometer. The energetic processing of CO:NH $_{3}$ ice mixtures mainly leads to the NH $_{2}$ CHO formation, along with its chemical derivatives such as isocyanic acid (HNCO) and cyanate ion (OCN $^{-}$ ). The formation kinetics of NH $_{2}$ CHO shows an explicit dependency on ice ratios and compositions; the highest yield is found in H $_{2}$ O-rich ice. The astronomical relevance of the resulting reaction network is discussed.

arXiv comment16 pages, 6 figures, 2 tables

Formation of the simplest amide in molecular clouds: formamide (NH $_{2}$ CHO) and its derivatives in H $_{2}$ O-rich and CO-rich interstellar ice analogs upon VUV irradiation

Abstract

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Formation of the simplest amide in molecular clouds: formamide (NH2​CHO) and its derivatives in H2​O-rich and CO-rich interstellar ice analogs upon VUV irradiation

Abstract

References in corpus (49)

Cited by in corpus (7)

Formation of the simplest amide in molecular clouds: formamide (NH $_{2}$ CHO) and its derivatives in H $_{2}$ O-rich and CO-rich interstellar ice analogs upon VUV irradiation