Laser-induced dry etching of integrated InP microlenses

Received: 4 June 1997/Accepted: 13 June 1997     

Construction and characterization of a high-flow, high-resolution ion mobility spectrometer for detection of explosives after personnel portal sampling

A novel analysis of explosives via the coupling of an airline passenger personnel portal with a high-flow (HF), high-resolution (HR) ion mobility spectrometry (IMS) was shown for the first time. The HF-HR-IMS utilized a novel ion aperture grid design with a (63)Ni ionization source while operating at ambient pressure in the positive ion mode at 200 degrees C. The HF-HR-IMS response characteristics of 2,4,6-trinitrotoluene (TNT), 4,6-dinitro-o-cresol (4,6DNOC), and cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) were investigated. Modifications made to the HF-HR-IMS exhaust and ionization source created an 800% increase in the total ion current (TIC), from 0.85 to 6.8 nA. This translated into a 65% ion response increase for TNT when compared with a traditional IMS. A mixture of TNT and (4,6DNOC) was used to successfully demonstrate the resolving power of the species with similar reduced mobility constants (K(o)), 1.54 and 1.59, respectively. The reactant ion (H(2)O)(n)H(+), peak was also used to measure the resolving power of the spectrometer while varying the internal diameter of three different aperture openings from 1.00 to 3.54cm. This provided a resolving power range of 50-60, double that typically achievable by commercial IMS instruments. Most important, these changes made in this new instrumental design can be implemented to all existing and future IMS's to greatly enhance the achievable IMS resolving power.     

The dynamic critical exponent of the three-dimensional Ising model

We measure the dynamic exponent of the three-dimensional Ising model using a damage spreading Monte Carlo approach as described by MacIsaac and Jan. We simulate systems fromL=5 toL=60 at the critical temperature,T _c =4.5115. We report a dynamic exponent,z=2.35±0.05, a value much larger than the consensus value of 2.02, whereas if we assume logarithmic corrections, we find thatz=2.05±0.05.     

Investigation of Fe-Mg-Alloys Produced by Ion Implantation

Iron and magnesium are insoluble elements with each other and there is no phase diagram. However, it is possible to produce artificial alloys by ion implantation, in this study by iron implantation into magnesium. Samples are investigated by conversion electron Moessbauer spectroscopy, Auger electron spectroscopy and x-ray diffraction. While at low doses gaussian shaped iron profiles and paramagnetic doublets as Mössbauer spectra are obtained, the iron concentration reaches at the highest dose 90 at.-% in maximum and the Mössbauer spectrum shows a dominant ferromagnetic fraction. The x-ray diffraction pattern let conclude that a dilated α-iron lattice is formed. Microhardness of all samples is clearly increased due to the implantation.     

Experience with neutron irradiated reactor pressure vessel steels-a Mössbauer study

The influence of neutron irradiation and post-irradiation heat treatment on the Mössbauer spectra of reactor pressure vessel steels is studied. Substantial changes in the materials are detected, but a final interpretation turned out to be impossible without performing further investigations.