Formation Mechanism for Interstellar Molecules

The gas phase production of molecules in dust clouds in interstellar space may occur largely as H2 formation on the interstellar grains, with relatively minor formation in the gas phase. The formation of more complex molecules, however, may be augmented by gas phase processes including (1) negative ions formed by radiative attachment of electrons, (2) direct radiative association of molecules and atoms, and (3) reaction of atoms and molecules with H3+ molecules.