33 research outputs found
Three Dimensional Secondary Ion Mass Spectrometry Imaging and Retrospective Depth Profiling
Secondary Ion Mass Spectrometry (SIMS) for three dimensional analysis of materials is an exciting and rapidly developing technique. We describe a framestore datasystem for ion microprobe instruments and present images and three dimensional SIMS data acquired and processed with this system. The concept of retrospective depth profiling is introduced, particularly as a means to optimise concentration detection limits. We examine the dependence of concentration detection limits on spatial resolution
Interaction potential between dynamic dipoles: polarized excitons in strong magnetic fields
The interaction potential of a two-dimensional system of excitons with
spatially separated electron-hole layers is considered in the strong magnetic
field limit. The excitons are assumed to have free dynamics in the -
plane, while being constrained or `polarized' in the direction. The model
simulates semiconductor double layer systems under strong magnetic field normal
to the layers. The {\em residual} interaction between excitons exhibits
interesting features, arising from the coupling of the center-of-mass and
internal degrees of freedom of the exciton in the magnetic field. This coupling
induces a dynamical dipole moment proportional to the center-of-mass magnetic
moment of the exciton. We show the explicit dependence of the inter-exciton
potential matrix elements, and discuss the underlying physics. The unusual
features of the interaction potential would be reflected in the collective
response and non-equilibrium properties of such system.Comment: REVTEX - 11 pages - 1 fi
RECENT DEVELOPMENTS IN THE APPLICATION OF LIQUID METAL ION SOURCES TO SIMS
High-brightness liquid metal ion sources (LMIS) allow SIMS microprobe analysis with 50 nm spatial resolution at current densities > 1A/cm2. Chemical imaging of matrix and trace elements on the submicron scale is now achieved using a digital image storage system allowing picture processing and direct comparison of SEM and SIMS images using colour overlays. While high-sensitivity quadrupole mass spectrometers have been developed for SIMS imaging. the ultimate in sensitivity requires magnetic or time-of-flight mass spectrometers