Synthesis of silicon-oxygen derivatives in quasi-interstellar conditions

Bombardment of a silicon target in high vacuum with a molecular beam of krypton in the presence of thermal oxygen atoms produces ions, which give a primary spectrum. The individual peaks of this spectrum are extracted and dissociated in a collision cell. Mass analysis of the ions and of their fragments leads to the identification of silicon-oxygen derivatives, the composition of which is established by using the presence of the three naturally occurring isotopes of silicon. The derivatives formed represent a series of silicon suboxides ranging from SiO to Si10O3.SiO2 is weak, as expected from its normal existence as a three-dimensional lattice, nor as isolated molecules. (C) Academie des sciences/Elsevier, Paris.