Highly efficient plasmonic nanofocusing is numerically predicted in a single step-like microslit, which is placed on a high-index dielectric layer. Because of the high throughput of the impinging light on the wide microslit, highly efficient nanofocusing is achieved in the proposed structure based on the multimode interferences in the microslits, the constructive interference between the transmitted light and the scattered surface plasmon polaritons, and the Fabry-Perot resonator effect in the high-index dielectric layer. Compared with previous nanofocusing structures containing plenty of substructures arranged laterally, the proposed structure has a much smaller lateral dimension because of the vertical arrangement of the microslits. This is of importance for realizing densely integrated plasmonic circuits. (C) 2013 Optical Society of America
Racemic β-hydroxy ketones were kinetically resoluted into the enantiopure isomers and (E)-α,β-unsaturated ketones using catalytic asymmetric intramolecular dehydration for the first time. Synthetic tetrapeptides were used to imitate fatty acid dehydratases to efficiently discriminate racemic β-hydroxy ketones, enantioselectively catalyze the intramolecular dehydration, and result in highly enantioenriched β-hydroxy and (E)-α,β-unsaturated ketones in the environmentally benign process. Mechanistically, the high discrimination of the racemic substrates and successive enantioselective dehydration are highly dependent on the cooperative catalysis of the NH2 and COOH groups of the peptide.
This letter reports a normally-OFF Al2O3/GaN gate-recessed MOSFET using a low-damage digital recess technique featuring multiple cycles of plasma oxidation and wet oxide removal process. The wet etching process eliminates the damage induced by plasma bombardment induced in conventional inductively coupled plasma dry etching process so that good surface morphology and high interface quality could be achieved. The fully recessed Al2O3/GaN MOSFET delivers true enhancement-mode operation with a threshold voltage of +1.7 V. The maximum output current density is 528 mA/mm at a positive gate bias of 8 V. A peak field-effect mobility of 251 cm(2)/V.s is obtained, indicating high-quality Al2O3/GaN interface.
