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Physical Chemistry Commons™

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2006

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Articles 121 - 122 of 122

Full-Text Articles in Physical Chemistry

A Chloride Selective Calix[4]Arene Optical Sensor Combining Urea Functionality With Pyrene Excimer Transduction, Benjamin Schazmann, Dermot Diamond Jan 2006

A Chloride Selective Calix[4]Arene Optical Sensor Combining Urea Functionality With Pyrene Excimer Transduction, Benjamin Schazmann, Dermot Diamond

Articles

A neutral 2-site chloride selective compound has been developed (3), based on a 1,3- alternate tetrasubstituted calix[4]arene providing a preorganised supramolecular scaffold. The resultant supramolecular cavity is amongst the first to combine urea functional groups bridged with single methylene spacers to pyrene moieties. It combines a naturally and synthetically proven H-bonding system with the elegant ratiometric fluorescent signalling properties of an intramolecular pyrene excimer system, triggered by conformational changes upon anion coordination. The excimer emission of 3 is quenched, with a simultaneous rise in the monomer emission solely by the chloride anion amongst a wide variety of anions tested. 3 …


Growth Of Ge Quantum Dots On Si(100)-(2×1) By Pulsed Laser Deposition, M. S. Hegazy, H. E. Elsayed-Ali Jan 2006

Growth Of Ge Quantum Dots On Si(100)-(2×1) By Pulsed Laser Deposition, M. S. Hegazy, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Self-assembled germanium quantum dots (QDs) were grown on Si(100)-(2×1) by pulsed laser deposition. In situ reflection-high energy electron diffraction (RHEED) and postdeposition atomic force microscopy are used to study the growth of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400 °C using a Q-switched Nd:yttrium aluminum garnet laser (λ= 1064 nm, 40 ns pulse width, 23 J/cm 2 fluence, and 10 Hz repetition rate). At low film thicknesses, hut clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing film thickness, …