Faraday cage angled-etching of nanostructures in bulk dielectrics

For many emerging optoelectronic materials, heteroepitaxial growth techniques do not offer the same high material quality afforded by bulk, single-crystal growth. However, the need for optical, electrical, or mechanical isolation at the nanoscale level often necessitates the use of a dissimilar substrate, upon which the active device layer stands. Faraday cage angled-etching (FCAE) obviates the need for these planar, thin-film technologies by enabling in-situ device release and isolation through an angled-etching process. By placing a Faraday cage around the sample during inductively-coupled plasma reactive ion etching (ICP-RIE), the etching plasma develops an equipotential at the cage surface, directing ions normal to its face. In this Article, the effects Faraday cage angle, mesh size, and sample placement have on etch angle, uniformity, and mask selectivity are investigated within a silicon etching platform. Simulation results qualitatively confirm experiments and help to clarify the physical mechanisms at work. These results will help guide FCAE process design across a wide range of material platforms

Design of photonic crystal microcavities for cavity QED

We discuss the optimization of optical microcavity designs based on 2D photonic crystals for the purpose of strong coupling between the cavity field and a single neutral atom trapped within a hole. We present numerical predictions for the quality factors and mode volumes of localized defect modes as a function of geometric parameters, and discuss some experimental challenges related to the coupling of a defect cavity to gas-phase atoms.Comment: 12 pages, 16 figure

Single Color Centers Implanted in Diamond Nanostructures

The development of materials processing techniques for optical diamond nanostructures containing a single color center is an important problem in quantum science and technology. In this work, we present the combination of ion implantation and top-down diamond nanofabrication in two scenarios: diamond nanopillars and diamond nanowires. The first device consists of a 'shallow' implant (~20nm) to generate Nitrogen-vacancy (NV) color centers near the top surface of the diamond crystal. Individual NV centers are then isolated mechanically by dry etching a regular array of nanopillars in the diamond surface. Photon anti-bunching measurements indicate that a high yield (>10%) of the devices contain a single NV center. The second device demonstrates 'deep' (~1\mu m) implantation of individual NV centers into pre-fabricated diamond nanowire. The high single photon flux of the nanowire geometry, combined with the low background fluorescence of the ultrapure diamond, allows us to sustain strong photon anti-bunching even at high pump powers.Comment: 20 pages, 7 figure

Reversed-phase thin-layer chromatography behavior of aldopentose derivatives

Quantitative structure-retention relationships (QSRR) have been used to study the chromatographic behavior of some aldopentose. The behavior of aldopentose derivatives was investigated by means of the reversed-phase thin-layer chromatography (RP TLC) on the silica gel impregnated with paraffin oil stationary phases. Binary mixtures of methanol-water, acetone-water and dioxane-water were used as mobile phases. Retention factors, RM0, corresponding to zero percent organic modifier in the aqueous mobile phase was determined. Lipophilicity C0 was calculated as the ratio of the intercept and slope values. There was satisfactory correlation between them and log P values calculated using different theoretical procedures. Some of these correlations offer very good predicting models, which are important for a better understanding of the relationships between chemical structure and retention. The study showed that the hydrophobic parameters RM0 and C0 can be used as a measures of lipophilicity of investigated compounds

Urinary cotinine as marker of passive tobacco smoking

Radi objektivizacije opasnosti pušenja roditelja po zdravlje njihove djece u 205 učenika oba spola, dobi 10-12 godina određena je, kolorimetrijskom metodom sa barbiturnom kiselinom (OBA), koncentracija kotinina u urinu. Dobiveni rezultati su korelirani sa podacima dobivenim iz ankete. Utvrđena je signifikantna razlika između srednje vrijednosti koncentracije kotinina za djecu roditelja nepušača (3,2 µmol/L) i djece u kojih puši jedan roditelj (5,8 µmol/L). Koncentracija kotinina je još veća ako puše oba roditelja (7,8 µmol/L) i najveća u djece, pasivnih pušača, koji nemaju posebnu sobu za učenje i spavanje, a oba su im roditelja pušači (9,2 µmol/L). Nije dobivena statistički značajna razlika u koncentracijama kotinina u djevojčica i dječaka.To provide an objective measure of the hazard smoking parents represent to their children\u27s health, cotinine concentration in urine was measured by the colorimetric method using barbituric acid (DBA). A total of 205 children, aged 10-12, were examined. The results of laboratory tests were correlated with the data collected by interview. A significant difference in the average value of cotinine concentration was demonstrated between the children whose parents did not smoke (3.2 µmol/L) and chose whose one parent smoked (5.8 µmol/L). An even larger concentration was recorded when both parents smoked (7.8 µmol/L). The largest cotinine concentration was determined in the urine of children - passive smokers whose both parents smoked and who did not have a room of their own (9.2 µmol/L). The difference in cotinine concentration between girls and boys was not statistically significant