Lyα irradiation of solid-state formamide

¹ Max Planck Institute für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: suhasaria@mpia.de
² INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Naples, Italy

Received: 28 February 2022
Accepted: 18 March 2022

Abstract

Context. Formamide (NH₂CHO) has been proposed as a potential prebiotic precursor in the scientific discourse on the origin of life. It has been observed in different environments in space, including protostellar regions and comets. The abundance and stability of NH₂CHO in the early stages of star formation can be better understood by incorporating the formation and destruction data in astrochemical models.

Aims. We carried out an experimental investigation to study the destruction of pure NH₂CHO ice at 12 K as a result of the interaction with Lyα (121.6 nm) photons.

Methods. We studied UV photo destruction of NH₂CHO using Fourier-transform infrared spectroscopy.

Results. After UV processing, the intensity of NH₂CHO IR bands decreased and new bands corresponding to HCN, CO, NH₄⁺ OCN⁻, HNCO, and CO₂ appeared in the spectrum. We then derived the destruction and cumulative product formation cross-sections.

Conclusions. A comparison of destruction rates derived from the cross-section in a cold and dense molecular cloud for different energetic processing agents reveals that UV photons induce NH₂CHO destruction at a level that is one order of magnitude greater than that affected by cosmic rays; however, it is three orders of magnitude lower than that of H atoms.