Elements Of X Ray Diffraction

Journal of Physics Condensed Matter: Preface

Inorganic semiconductor nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating the size and dimensionality dependence of their properties for potential applications. The use of such nanostructures with tailored geometries as building blocks is also expected to play crucial roles in future nanodevices. Since the discovery of carbon nanotubes much attention has been paid to exploring the usage of inorganic semiconductor nanostructures as field-emitters due to their low work functions, high aspect ratios and mechanical stabilities, and high electrical and thermal conductivities. This article provides a comprehensive review of the state-of-the-art research activities in the field. It mainly focuses on the most widely studied inorganic nanostructures, such as ZnO, ZnS, Si, WO3, AlN, SiC, and their field-emission properties. We begin with a survey of inorganic semiconductor nanostructures and the field-emission principle, and then discuss the recent progresses on several kinds of important nanostructures and their field-emission characteristics in detail and overview some additional inorganic semiconducting nanomaterials in short. Finally, we conclude this review with some perspectives and outlook on the future developments in this area.

Inorganic semiconductor nanostructures and their field-emission applications

We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L(1)ZnOEt)(2) (L(1) = 2,4-di-tert-butyl-6-{[(2'-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L(1)ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded M(n) as high as 130 kg mol(-)(1). The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L(1)ZnOEt to be distinguished and the empirical rate law to be elucidated, -d[LA]/dt = k(p)[L(1)ZnOEt][LA]. These studies also showed that L(1)ZnOEt polymerizes lactide at a rate faster than any other Zn-containing system reported previously. This work provides important mechanistic information pertaining to the polymerization of lactide and other cyclic esters by discrete metal alkoxide complexes.

Highly active zinc catalyst for the controlled polymerization of lactide.

A Review on Surface-Enhanced Raman Scattering.

We review the performance and applications of an extreme ultraviolet interference lithography (EUV-IL) system built at the Swiss Light Source of the Paul Scherrer Institut (Villigen, Switzerland). The interferometer uses fully coherent radiation from an undulator source. 1-D (line/space) and 2-D (dot/hole arrays) patterns are obtained with a transmission-diffraction-grating type of interferometer. Features with sizes in the range from one micrometer down to the 10-nm scale can be printed in a variety of resists. The highest resolution of 11-nm half-pitch line/space patterns obtained with this method represents a current record for photon based lithography. Thanks to the excellent performance of the system in terms of pattern resolution, uniformity, size of the patterned area, and the throughput, the system has been used in numerous applications. Here we demonstrate the versatility and effectiveness of this emerging nanolithography method through a review of some of the applications, namely, fabrication of metallic and magnetic nanodevice components, self-assembly of Si/Ge quantum dots, chemical patterning of self-assembled monolayers (SAM), and radiation grafting of polymers. (c) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3116559]

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Extreme ultraviolet interference lithography at the Paul Scherrer Institut

The dispersion of metal nanoparticles on reduced graphene oxide (RGO) sheets potentially provides a new way to develop novel catalytic, magnetic, adsorbing, and electrode materials. In this work, we report the structural and magnetic properties of RGO/metal (Bi, Pt, Ni, and Pt-Ni) nanocomposites. Such nanocomposites are successfully synthesized by a facile in situ co-reduction route. The structure, composition, and morphology of the synthesized materials are systematically investigated by X-ray diffraction, inductively coupled plasma-atomic emission spectrometer , and high resolution transmission electronic microscopy. The M–H curve and zero-field-cooled and field-cooled data for RGO, RGO/Ni, and RGO/Pt-Ni nanocomposites exhibit ferromagnetic behaviour. RGO/Pt nanocomposite shows diamagnetic, while RGO/Bi nanocomposite shows lower magnetization compared to that of RGO. Detailed magnetic studies on these nanocomposites and its correlation with microstructural features are presented here.

Magnetic behavior of reduced graphene oxide/metal nanocomposites

Synthesis and characterization of ZnO thin films for UV laser

Densely packed plasmonic particle arrays are investigated for biosensing applications. Such particle arrays exhibit interparticle optical coupling creating a strong field between the particles, which is useful for sensing purposes. The sensor properties, such as bulk sensitivity, layer sensitivity, and the depth of sensitivity are investigated with the aid of a multiple multipole program. Sensitivity to the analyte with low concentration is also examined by a dynamic adsorption processes. The detectable concentration limit of streptavidin within 3000 s in the detection system is expected from the signal-to-noise to be less than 150 pM.

Biosensing by Densely Packed and Optically Coupled Plasmonic Particle Arrays

Object Lipomas of the spinal cord are often a component of spinal dysraphic states. Nondysraphic intramedullary spinal cord lipomas are rare, and their presentation, in the form of gradually worsening myelopathy, is nonspecific. The authors report on the methods used for diagnosis and treatment in patients presenting with these lesions at their institution, and they review the relevant literature. Methods The authors treated 14 patients who presented with intramedullary lipomas over a period of 12 years. None of these patients had segmentation anomaly or dysraphism of the spine, or any hindbrain anomaly. Admission magnetic resonance images were diagnostic in all patients. All tumors were located dorsally in the spinal cord, the majority of them in the cervicodorsal cord. The lipomas were partially excised with the help of a carbon dioxide laser in all patients in an attempt to preserve neurological function. All patients attained improvement in their sensory and motor symptoms. Conclusions Because these l...

/pdf/nondysraphic-intramedullary-spinal-cord-lipomas-a-review-40bexnn95s.pdf

Pratap K. Sahoo

Papers

Extreme ultraviolet interference lithography at the Paul Scherrer Institut

Magnetic behavior of reduced graphene oxide/metal nanocomposites

Synthesis and characterization of ZnO thin films for UV laser

Biosensing by Densely Packed and Optically Coupled Plasmonic Particle Arrays

Nondysraphic intramedullary spinal cord lipomas: a review.