Photolysis of Astrophysically Relevant Acrylonitrile: A Matrix Experimental Study

This report documents the photochemical study of H2C=C(H)CN (acrylonitrile) trapped in low-temperature argon matrices and irradiated with a microwave-discharge hydrogen-flow lamp (lambda > 120 nm). We succeeded in identifying H2C=C(H)NC (isoacrylonitrile) as a photoproduct. HC3N (cyanoacetylene), C2H2:HCN (acetylene:hydrogen cyanide), and C2H2:HNC (acetylene:hydrogen isocyanide) complexes, which are molecules detected in molecular clouds or in the Titan atmosphere, were also identified. No imine product was observed, but other compounds coming from the HC3N photolysis have been found. Fourier transform infrared measurements and H-2 substitution experiments coupled with density functional theory calculations (B3LYP/6-31G**) were performed to confirm the spectral assignments of the photochemical products and intermediate species.