Ko. Lozhkin et al., ELECTRON-CAPTURE AND MULTIPLE IONIZATION IN COLLISIONS OF FAST H+ ANDHE2+ IONS WITH GALLIUM ATOMS, Journal of physics. B, Atomic molecular and optical physics, 30(7), 1997, pp. 1785-1798
A crossed-beam technique incorporating time-of-flight analysis and coi
ncidence counting of the collision products has been used to study ele
ctron capture, and pure ionization of ground-state gallium atoms in co
llisions with H+ and He2+ ions. Cross sections leading to the formatio
n of up to six-fold ionized gallium in electron capture and up to four
-fold ionized gallium through pure ionization have been determined wit
hin the energy range 38-1440 keV amu(-1). Pure ionization rather than
electron capture is found to provide the main contribution to Gaq+ for
mation over most of the energy range considered. A notable feature of
the electron capture data is the dominance of the Ga2+ transfer ioniza
tion contribution which is believed tc be indicative of the important
role of Auger ionization processes. Calculations based on an independe
nt electron model of ionization (which have provided a good descriptio
n of our previous measurements in Fe and Cu) are shown to fit our meas
ured pure ionization cross sections in Ga very satisfactorily. In the
case of electron capture, when the model is modified to take some acco
unt of Auger ionization, Gaq+ formation is described reasonably for H impact but with only limited success for He2+ impact.