The Formation of Molecular Compounds following Radiolysis of Solid Hydrogen Cyanide

Low-temperature HCN radiolysis (conditions close to those in cosmic space) leads to formation of different molecular compounds; conjugated polymers [C=N–C=N]n, with conjugated chain growth, are formed (colour change orange → brown → black). The polymer gives a singlet EPR signal typical of polyconjugated systems, and crystals of 1,2-diaminomalonodinitrile are also formed. Electrical breakdowns and glow are observed on freezing the HCN; this Is connected with a brittle fracture of HCN crystals leading to electrical charge separation. The freezing out of HCN onto grains of interstellar dust under cosmic conditions would lead to effective coagulation of the dissipated substance at the expense of electrostatic attraction.