Photolysis of acetonitrile in a water-rich ice as a source of complex organic molecules: CH₃CN and H₂O:CH₃CN ices

Context. Many C-, O-, and H-containing complex organic molecules (COMs) have been observed in the interstellar medium (ISM) their formation has investigated laboratory experiments. An increasing number of recent detections large N-bearing COMs motivates our experimental investigation chemical origin. Aims. We investigate potential role acetonitrile (CH 3 CN) as a parent molecule to COMs, motivated by its omnipresence ISM structural similarity another well-known precursor species, CH OH. The aim present work is characterize complexity that can result from vacuum UV photolysis pure CN ice more realistic mixture H 2 O:CH CN. Methods. mixtures were irradiated at 20 K. Laser desorption post ionization time-of-flight mass spectrometry was used detect newly formed situ. examined water chemistry ices through an analysis two different ratios (1:1 20:1). Results. find excellent larger nitrogen-containing including CN, NCCN/CNCN, NCCH During ice, derivatives play key with functional groups of: imines, amines, amides, nitriles, carboxylic acids, alcohols. discuss possible pathways for recently detected ISM.