Lyα Irradiation Of Solid-state Formamide

By Keith Cowing
March 24, 2022
Filed under
Lyα Irradiation Of Solid-state Formamide
Mid-IR spectrum of a 29.5 ML thick NH2CHO film at 12 K as deposited (black line) and after UV irradiation of 6.5×1018 photons cm−2 (red line). Symbols ν and δ stand for stretching and bending modes, respectively. The subindex a, s, and i denotes antisymmetric, symmetric, and in-plane mode, respectively. The spectrum of a CsI substrate after UV irradiation of 6.5×1018 photons cm−2 (blue line) is also shown for comparison. The red and blue curves are offset in ordinate by 0.0055 and -0.005, respectively, for the sake of clarity.

Formamide (NH2CHO), a potential prebiotic precursor, has been proposed to play an important role in the context of origin of life on our planet. It has been observed in different environments in space including the 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 the astrochemical models. We carried out an experimental investigation to study the destruction of pure NH2CHO ice at 12 K by the interaction of Lyα (121.6 nm) photons. The UV photo destruction of NH2CHO was studied using Fourier-transform infrared spectroscopy.

After UV processing, the intensity of NH2CHO IR bands decreases and new bands corresponding to HCN, CO, NH+4 OCN−, HNCO, and CO2 appeared in the spectrum. Destruction and cumulative product formation cross-sections were derived. The comparison of destruction rate derived from the cross-section in cold and dense molecular cloud for different energetic processing agents, reveals that UV photons induces an order of magnitude higher NH2CHO destruction than cosmic rays, but three orders of magnitude lower than for H atoms.

T. Suhasaria, V. Mennella

Comments: 7 pages, 4 figures, 2 tables
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2203.12390 [astro-ph.IM] (or arXiv:2203.12390v1 [astro-ph.IM] for this version)
Submission history
From: Tushar Suhasaria Dr
[v1] Wed, 23 Mar 2022 13:06:25 UTC (170 KB)
Astrobiology, Astrochemistry,

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.