Electron detachment of Si- by He, Ne, and Ar

The cross sections for electron detachment of Si^- were measured for He, Ne, and Ar targets at relative velocities in the 0.25-1.4 a.u. range. Argon target cross sections were measured using Si^- ions from two different origins, the results agreeing well with each other and with literature values. The velocity dependence of the Si^- cross sections is strikingly similar to that of known H^- results, with the former being consistently larger than the latter and, at large velocities, differing by a multiplicative constant.