Limits of applicability of a time-of-flight ion-mass analyzer in uncovering partial currents of ions emitted by pulsed laser ion sources
Annotatsiya
We report an analysis of the experimental determination of partial currents of Fe q+ ions (1≤q≤4) generated by a Nd:YAG laser (λ=1064 nm, I L ≈ 1×1010 W/cm2) irradiating the (111) surface of Fe and Fe−2 mass% Si single crystals. The emission of Fe q+ ions and of ionized admixtures of silicon, carbon, oxygen and hydrogen is investigated with the use of ion collectors (IC) and a cylindrical electrostatic ion mass analyzer (CEA). The partial currents of ion species were reconstructed from a set of CEA spectra obtained by changing the voltage between the CEA's cylindrical deflecting plates. The basic difference between the sum of all the reconstructed partial currents and the corresponding IC current is analyzed and the reasons for differences are specified. A numerical deconvolution of IC signals as an alternative to this method is also applied. In this way, hidden partial ion currents are uncovered using an explicit analytical expression to describe the partial currents.