title: Interstellar chemistry.
abstract: In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature.
authors.affiliation: Department of Chemistry, Harvard University, Cambridge, MA 02138, USA. billk@otto.harvard.edu
authors.forename: William
authors.initials: W
authors.lastname: Klemperer
mesh_terms: D001256:Astronomy / Q000295:instrumentation / Q000379:methods; D002244:Carbon / Q000737:chemistry; D002625:Chemistry, Organic; D019443:Cosmic Dust; D019418:Evolution, Chemical; D005118:Extraterrestrial Environment / Q000737:chemistry*; D006371:Helium / Q000737:chemistry; D006801:Humans; D006859:Hydrogen / Q000737:chemistry; D055601:Organic Chemistry Phenomena; D000069497:Origin of Life; D013816:Thermodynamics
chemical_list: D019443:Cosmic Dust; D006371:Helium; D002244:Carbon; D006859:Hydrogen