New experiments and interpretations concerning the "XCN" band in interstellar ice analogues

Evidence for the formation of OCN- in interstellar ice analogues is summari zed with an emphasis on the recent experiments of Demyk et al. (1998). Thei r experiments are reinterpreted in terms of two different types of chemical reactions, acid-base and oxidation-reduction. New spectra of UV-photolyzed and p(+)-irradiated ices are presented, and reasons for similarities consi dered. The role of e(-) and H+ scavengers in revealing ice photo- and radia tion chemistries is stressed, and it is concluded that electron-transfer re actions may play a more important role than commonly thought.