Emission cross sections in low-energy collisions between He+, Ne+ ions and CF4 molecule

Emission cross sections (Qem) of CF+4(, ; 200–500 nm), CF+4(, 350–440 nm), F(3p 4Do7/2–3s 4P5/2; 685.6 nm), He(3d 3D–2p 3Po; 587.6 nm), and Ne(3p 2[5/2]–3s 2[3/2]; 640.2 nm) produced in charge-exchange collisions between He+ and Ne+ and CF4 molecule were measured in the energy range below 5000 eV down to 1 eV (ELab). Emission cross sections of F(3s 2P–2p5 2Po; 95.5 nm) and F(3s 4P–2p5 2Po; 97.5 nm) were also measured in He++CF4. No emission peaks were observed in the spectrum of Ar++CF4 (ELab = 2000 eV) in the wavelength range of 200–800 nm. The emission cross section of CF+4(, ; 200–500 nm) observed in Ne++CF4 decreased with increasing the energy with a relation of Qem ∝ E−1/2CM up to 60 eV, whereas it increased with increasing the energy above 100 eV. This result agreed well with one of Sasaki et al [1]. It was concluded that such dependence below 60 eV originated from an orbiting resonance into Ne+CF+4 channel. Emission cross sections of F, He and Ne rapidly increased with increasing the energy from the near thresholds.