A measurement of the cross section for ionisation of Ta+ by electron impact

摘要: The absolute cross section for the ionisation process Ta++e to Ta2++2e has been measured at electron energies ranging from threshold 2000 eV using crossed electron-ion beams technique. total error in is estimated be +or-4.2% or less a 90% confidence level above 16 eV. results show that Ta+ beam contains significant fractions of metastable ions, 3F, 3P and possibly higher states, addition 5F ground-state ions. In comparison with experimental data, scaled Born calculation McGuire, taking into account 6s 5d electrons 5F, 3F states significantly underestimates section, particularly low energies. There evidence excitation-autoionisation processes enhance near peak this accounts part discrepancy. ion found 15.2+or-0.3 eV, which smaller than spectroscopic value 16.2+or-0.5 obtained by Finkelnburg Humbach.