Symmetric resonance multiple charge transfer of Neq+and Arq+(q⩽4)

Cross sections for resonance charge transfer processes, A q+ +A to A+A q+ , have been measured for Ne 1-4+ and Ar 1-4+ at ion acceleration voltages of 2, 3 and 4 kV. The cross sections obtained at 2 kV are 6.9*10 -16 , 1.74*10 -16 , 4.9*10 -17 and 3.4*10 -18 cm 2 for Ne + , Ne 2+ , Ne 3+ and Ne 4+ , respectively, and 2.4*10 -15 , 5.5*10 -16 , 9.0*10 -17 and 3*10 -18 cm 2 for Ar + , Ar 2+ , Ar 3+ and Ar 4+ , respectively. This is the first measurement of resonance charge transfer cross sections for quadruply charged ions. The results obtained are discussed in terms of the total ionisation energies Sigma j q I j of the ions, where I j is the jth ionisation potential. A concept of the 'survival factor' is introduced.