| Popis: |
Absolute doubly differential cross sections for electron emission are presented for 0.5-MeV/u multicharged ion-atom collisions. The collision systems investigated are ${\mathrm{B}}^{\mathit{q}+}$, ${\mathrm{C}}^{\mathit{q}+}$ (q=2--5) and ${\mathrm{O}}^{\mathit{q}+}$, ${\mathrm{F}}^{\mathit{q}+}$ (q=3--6) projectiles impacting on helium and ${\mathrm{C}}^{\mathit{q}+}$ (q=2--5) ions impacting on neon and argon targets. Laboratory electron emission angles between 10\ifmmode^\circ\else\textdegree\fi{} and 60\ifmmode^\circ\else\textdegree\fi{} were studied. Under the assumption that the cross sections scale with the square of an effective projectile charge, ${\mathit{Z}}_{\mathit{e}\mathit{f}\mathit{f}}$(\ensuremath{\varepsilon},\ensuremath{\theta}), the scaling was investigated as a function of emitted electron velocity and angle. For distant collisions (low-energy electron emission), we find that ${\mathit{Z}}_{\mathit{e}\mathit{f}\mathit{f}}$(\ensuremath{\varepsilon},\ensuremath{\theta})gq for small q. For the highest values of q investigated, ${\mathit{Z}}_{\mathit{e}\mathit{f}\mathit{f}}$(\ensuremath{\varepsilon},\ensuremath{\theta}) was found to be smaller than the net projectile charge q. The effective projectile charges may be subject to a systematic underestimation since they were determined by referencing the partially stripped ion impact data to fully stripped boron, rather than proton, impact cross sections. In the binary-encounter region, the present data confirm previously observed features--namely that the emission increases as q decreases. For the helium target, the qualitative behavior is roughly in accordance with predictions by Schulz and Olson [J. Phys. B 24, 3409 (1991)]. Neon and argon targets also demonstrate these features, but less dramatically than helium. |
