Ionization reactions of halogens and metal polyhalides with alkali atoms and dimers: Absolute cross sections

Abstract

Absolute cross sections for the chemi-ionization of K2 and Cs2 with F2, Cl2, Br2, I2, SnCl4, MoF6, and UF6, and of K and Cs with UF6, are measured. A supersonic alkali beam passes through a gas cell and the product ions are measured. The relative error in the cross sections is about 30% while the absolute values are within a factor of two. For the halogens the cross sections (in Å2) range from 111 for Cs2–Br2 to 0.07 for Cs2–F2. An explanation is offered for these large differences. The dimer cross sections with the polyhalides range from 6 to 0.06. With UF6 the cross sections with K and Cs are much smaller than those for K2 and Cs2.