The absolute total cross-sections of the charge transfer and the total luminescence in 1 keV H2+–H2 collisions

Abstract

The processes in the H₂⁺–H₂ system at 1 keV laboratory energy have been analysed as a function of target pressure, in the range 0 to 5.32 Pa. The charge transfer cross section was determined based on the attenuation of the ion beam along a defined path. The resulting value is σ_T = (6.2 ± 0.2) × 10⁻²⁰ m². The second analysed problem was the total luminescence emitted in the 200–600 nm range by the interacting particles along the ion beam path. The pressure dependence of the optical signal was compared with computer-simulated light intensities calculated using different values of the cross sections for different luminescence precursors. It is not possible to describe this relationship using a single cross-section. It was found that, for pressures above 1 Pa, the main component of the emitted light is the luminescence of the target molecules excited by secondary collisions with the projectile beam formed after the first collision. The determined cross section for this process is σ_LSP = (1.5 ± 0.5) × 10⁻²⁰ m².