ABSTRACT
In an atom probe, molecular ions can be field evaporated from the analyzed material and, then, can dissociate under the very intense electric field close to the field emitter. In this work, field evaporation of ZnO reveals the emission of Zn2O2(2+) ions and their dissociation into ZnO(+) ions. It is shown that the repulsion between the produced ZnO(+) ions is large enough to have a measurable effect on both the ion trajectories and times of flight. Comparison with numerical simulations of the ion trajectories gives information on the lifetime of the parent ions, the energy released by the dissociation and repulsion, and also the dissociation direction. This study not only opens the way to a new method to obtain information on the behavior of molecular ions in high electric fields by using an atom probe, but also opens up the interesting perspective to apply this technique to a wide class of materials and molecules.
Subject(s)
Electricity , Zinc Oxide/chemistry , Water/chemistryABSTRACT
The development of laser-assisted atom probes makes it possible, in principle, to exploit the femtosecond laser pulse not only for triggering ion evaporation from a nanometric field emission tip, but also for generating photons via the radiative recombination of electron-hole pairs in tips made of dielectric materials. In this article we demonstrate a first step towards a correlation of micro-photoluminescence (µ-PL) and laser-assisted tomographic atom probe (LA-TAP) analysis applied separately on the same objects, namely on ZnO microwires. In particular, we assess that the use of the focused ion beam (FIB) tip preparation method significantly degrades the radiative recombination yield of the analyzed microwires. We discuss the strategies to avoid the FIB-induced damage on the optical properties of the sample and how to get beyond the correlated µ-PL and LA-TAP analysis with a coupled approach allowing to perform the two analyses within the same instrument.
