Charge Transfer between Ground‐State Si3+and He at Electron‐Volt Energies

The charge-transfer rate coefficient for the reaction Si{sup 3+}(3s{sup 2}S)+He{r_arrow}products is measured by means of a combined technique of laser ablation and ion storage. A cylindrical radio-frequency ion trap was used to store Si{sup 3+} ions produced by laser ablation of solid silicon targets. The rate coefficient of the reaction was derived from the decay rate of the ion signal. The measured rate coefficient is 6.27{sub {minus}0.52}{sup +0.68}{times}10{sup {minus}10}cm{sup 3}s{sup {minus}1} at T{sub equiv}=3.9{times}10{sup 3}K. This value is about 30{percent} higher than the Landau-Zener calculation of Butler & Dalgarno and is larger by about a factor of 3 than the recent full quantal calculation of Honvault {ital et al.} {copyright} {ital 1997} {ital The American Astronomical Society}