Pulsed-laser-stimulated field ion emission from metal and semiconductor surfaces: A time-of-flight study of the formation of atomic, molecular, and cluster ions

摘要: In field ion emission, ions are formed beyond a critical distance from the emitter surface. This is imposed by condition that energy level of tunneling atomic electron must line up with vacant electronic state in solid. As result field-emitted exhibit deficit distribution. The related to binding and ionization emitted atoms, work function or affinity A time-of-flight measurement distribution various types both metal semiconductor surfaces has been made using pulsed-laser atom probe. From mechanisms formation pulsed-laser-stimulated including novel molecular cluster such as ${\mathrm{D}}_{3}^{+}$, ${\mathrm{N}}_{2}$${\mathrm{H}}^{+}$, ${\mathrm{ArH}}^{+}$, ${\mathrm{RhHe}}^{2+}$, ${\mathrm{PtHe}}^{2+}$, ${\mathrm{PtHe}}_{2}^{2+}$,${\mathrm{Si}}_{1\mathrm{t}\mathrm{o}\phantom{\rule{0ex}{0ex}}11}^{2+}$, ${\mathrm{Si}}_{1\phantom{\rule{0ex}{0ex}}\mathrm{t}\mathrm{o}\phantom{\rule{0ex}{0ex}}6}^{+}$, etc., investigated. It found photoexcitation plays an important role evaporation silicon. Pulsed-laser Si can be sustained almost indefinitely field-gradient- temperature-pulse-induced surface diffusion atoms shank. most abundant Si-cluster ${\mathrm{Si}}_{4}^{2+}$, ${\mathrm{Si}}_{5}^{2+}$, ${\mathrm{Si}}_{6}^{2+}$. These clusters ${\mathrm{Si}}_{13}^{4+}$ only small, symmetrically structured units one remove crystal. numbers 4, 5, 6, 13 magic formation. number 3 for 2+ ions. higher energies heavy data which not readily available, also derived field-evaporated