Window resonance in photodetachment of the negative silicon ion: strong interaction of the 3p continuum with the 3s to 3p shape resonance

Photodetachment cross section measurements have been performed on the Si-(3s23p34S) ion using a pulsed dye laser and non-linear optical techniques in the photon energy region close to the 3s threshold. A deep window resonance observed at a photon energy of 5.2 eV is a clear manifestation of electron correlation resulting from the interaction of the 3p to epsilon s, epsilon d continua with the 3s23p3 to 3s3p4 autodetaching resonance. The experimental resonance parameters are compared with theoretical predictions.