Nanoscience and Nanotechnology Commons^™

Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. Casse, W. Lu, Y. Huang, E. Gultepe, L. Menon, S. Sridhar

Srinivas Sridhar

Super-resolution imaging beyond Abbe's diffraction limit can be achieved by utilizing an optical medium or "metamaterial" that can either amplify or transport the decaying near-field evanescent waves that carry subwavelength features of objects. Earlier approaches at optical frequencies mostly utilized the amplification of evanescent waves in thin metallic films or metal-dielectric multilayers, but were restricted to very small thicknesses (⪡λ, wavelength) and accordingly short object-image distances, due to losses in the material. Here, we present an experimental demonstration of super-resolution imaging by a low-loss three-dimensional metamaterial nanolens consisting of aligned gold nanowires embedded in a porous alumina matrix. This composite …

Large Coercivity In Nanostructured Rare-Earth-Free Mnₓga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal

Donald Heiman

The magnetic hysteresis of MnₓGa films exhibit remarkably large coercive fields as high as μₒHC=2.5 T when fabricated with nanoscale particles of a suitable size and orientation. This coercivity is an order of magnitude larger than in well-ordered epitaxial film counterparts and bulk materials. The enhanced coercivity is attributed to the combination of large magnetocrystalline anisotropy and ~50-100 nm size nanoparticles. The large coercivity is also replicated in the electrical properties through the anomalous Hall effect. The magnitude of the coercivity approaches that found in rare-earth magnets, making them attractive for rare-earth-free magnet applications.

Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. Bennett, L. Menon, D. Heiman

Donald Heiman

Ordered arrays of GaMnAs magnetic semiconductor nanodots have been fabricated using anodic porous alumina templates as etch masks. The magnetic behavior is studied for prepared arrays with 40 nm dot diameter, 15 nm dot thickness, and 80 nm periodicity. The disklike nanodots exhibit an easy axis for fields applied in the radial direction and a hard axis in the smaller direction. In the radial direction superparamagnetism is observed with a blocking temperature of 30 K. The fabrication technique is convenient for preparing nanodot arrays of compound semiconductors that cannot be formed by self-assembly techniques.

Multimodal Grain Size Distribution And High Hardness In Fine Grained Tungsten Fabricated By Spark Plasma Sintering, Osman El-Atwani, D.V. Quach, Mert Efe, Patrick Cantwell, Bryan Heim, Bradley Schultz, Eric Stach, Joanna Groza, Jean Allain

Osman El-Atwani

Preparation of fine grained, hard and ductile pure tungsten for future fusion reactor applications was tested using the bottom-up approach via powder consolidation by spark plasma sintering (SPS) at different temperature (1300-1800 degrees C) and pressure (90-266 MPa) conditions. Pure tungsten powders with an average particle size of about 1 mu m were sintered to high density (about 94%) with almost no grain growth at a temperature below 1400 degrees C and an applied pressure up to 266 MPa. These samples had a multi-modal grain size distribution (resembling the size distribution of the initial powder) and a very high Vickers …

Analysis Of Scratches Formed On Oxide Surface During Chemical Mechanical Planarization, Jae-Gon Choi, Y. Prasad, In-Kwon Kim, In-Gon Kim, Woo-Jin Kim, Ahmed Busnaina, Jin-Goo Park

Jin-Goo Park

Scratch formation on patterned oxide wafers during the chemical mechanical planarization process was investigated. Silica and ceria slurries were used for polishing the experiments to observe the effect of abrasives on the scratch formation. Interlevel dielectric patterned wafers were used to study the scratch dimensions, and shallow trench isolation patterned wafers were used to study the effect of polishing parameters, such as pressure and rotational speed (head/platen). Similar shapes of scratches (chatter type) were observed with both types of slurries. The length of the scratch formed might be related to the period of contact between the wafer and the pad. …

The Effect Of Frictional And Adhesion Forces Attributed To Slurry Particles On The Surface Quality Of Polished Copper, Yi-Koan Hong, Ja-Hyung Han, Tae-Gon Kim, Jin-Goo Park, Ahmed Busnaina

Jin-Goo Park

The effect of frictional and adhesion forces attributed to slurry particles on the quality of copper surfaces was experimentally investigated during copper chemical mechanical planarization process. The highest frictional force of 9 Kgf and adhesion force of 5.83 nN were observed in a deionized water-based alumina slurry. On the other hand, the smallest frictional force of 4 Kgf and adhesion force of 0.38 nN were measured in an alumina slurry containing citric acid. However, frictional (6 Kgf) and adhesion (1 nN) forces of silica particles in the slurry were not significantly changed regardless of the addition of citric acid. These …

Electrodeposition Study Of Odn : Swcnt Hybrids On Gold Substrates, Roya Lahiji, Bridget Dolash, Jennifer Mcdonald, Dmitry Zemlyanov, Donald Bergstrom, R. Reifenberger

Dmitry Yurievich Zemlyanov

Sonication of short single-stranded DNA (oligodeoxyribonucleotide; ODN) with Single-Walled Carbon Nanotubes (SWCNTs) greatly facilitates the dispersion of SWCNTs from entangled ropes in an aqueous solution, creating ODN:SWCNT hybrids. Electrodeposition has been investigated to determine if well-dispersed ODN :SWCNT hybrids on a metal substrate can be created. Preliminary studies indicate that electrodeposition using an Au substrate held at +0.5 V produces ODN: SWCNT hybrids that are uniformly deposited across the Au substrate. This result can be compared to samples produced by drop casting and evaporation techniques which yield a thick tangled mat of ODN :SWCNT hybrids across the substrate. The resulting …

Controllable Surface Expression Of Bioactive Peptides Incorporated Into A Silica Thin Film Matrix, Sabrina Jedlicka, Jenna Rickus, Dmitry Zemlyanov

Dmitry Yurievich Zemlyanov

Mammalian cell culture platforms often require biomolecular modification to enhance cell adhesion and proliferation, Often, these modifications are performed using self-assembled monolayers or whole protein coatings, Such its collagen. These protocols are inherently useful but generally suffer from repeatability. Undesirable conditions during self-assembly can lead to complications in the surface presentation of the biological ligands. Whole proteins are often unstable and derived from animal sources, making them less attractive for tissue engineering applications. As the biological effect of the material often depends strongly on the concentration of the integrated ligand(s), any complication due to synthesis or stability can lead to …

Dissociation Of Water On The Surface Of Organic Salts Studied By X-Ray Photoelectron Spectroscopy, Peter Guerrieri, Dmitry Zemlyanov, Lynn Taylor

Dmitry Yurievich Zemlyanov

Water dissociation has important implications for numerous chemical processes. Although extensively studied on metals and to some extent on inorganic salts, this phenomenon has not yet been shown to occur on organic surfaces. Herein, the ability of two crystalline organic hydrochloride salts to induce water dissociation at their surface was demonstrated. Using a modified X-ray photoelectron spectroscopy setup, the oxygen lacking crystalline organic salts were exposed to high water vapor pressures within an environment sealed from ambient air. Thus, the O(1s) peak resulting from exposure to water vapor at room temperature could be unambiguously assigned to dissociated water, a phenomenon …

Assessment Of The Passivation Capabilities Of Two Different Covalent Chemical Modifications On Gap(100), David Richards, Dmitry Zemlyanov, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Gallium phosphide is a semiconductor material that can be used for the fabrication of optoelectronic devices. The report compares the ability of two similar organic molecules to form covalent bonds with the GaP(100) surface. Undecenoic acid (UDA) is a terminal alkene that can potentially form Ga-C bonds, and mercaptoundecanoic acid (MUA) is a thiol that can be used to generate Ga-S bonds. The chemical passivation capabilities of the functionalized surfaces exposed to different media were investigated by contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Toxicity levels, which are important for sensing applications. were evaluated by …

Dna Immobilization On Gap(100) Investigated By Kelvin Probe Force Microscopy, David Richards, Dmitry Zemlyanov, Rafay Asrar, Yena Chokshi, Emily Cook, Thomas Hinton, Xinran Lu, Viet Nguyen, Neil Patel, Jonathan Usher, Sriram Vaidyanathan, David Yeung, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Understanding changes in the properties of semiconductor materials after immobilization of biomolecules on the surface is essential for the fabrication of well-tuned and programmable devices. The work examines changes in the properties of gallium phosphide (GaP) after modification with an organic linker, a single stranded DNA, and its complementary strand. We investigated changes in surface potential with Kelvin probe force microscopy (KPFM). Analysis revealed that a more ordered adlayer of ssDNA was present when a lower concentration of linker molecule was used. KPFM data combined with coverage data obtained from X-ray photoelectron spectroscopy (XPS) further confirmed this result. Successful hybridization …

Electron Spectroscopy A New Window Opens, Dmitry Zemlyanov

Dmitry Yurievich Zemlyanov

No abstract provided.

Afm Study Of Ridges In Few-Layer Epitaxial Graphene Grown On The Carbon-Face Of 4h-Sic(000(1)Over-Bar), Gyan Prakash, Michael Capano, Michael Bolen, Dmitry Zemlyanov, R. Reifenberger

Dmitry Yurievich Zemlyanov

A characterization of the graphitic overlayer that forms on 4H-SiC(000 (1) over bar) substrates heated for ten minutes to temperatures T > 1350 degrees C under vacuum conditions has been performed. X-ray photoelectron spectroscopy of the C-face reveals the presence of graphitic carbon with a thickness that increases with growth temperature. Parallel atomic force microscope (AFM) studies find a mesh-like network of ridges with high curvature that bound atomically flat, tile-like facets of few-layer graphene (FLG). By imaging the network that develops on FLG, it is possible to map out the regions where the elastic energy is concentrated.

Temperature-Induced Modifications Of Pdzn Layers On Pd(111), W Stadlmayr, Ch Rameshan, C Weilach, H Lorenz, M Haevecker, R Blume, T Rocha, D Teschner, A Knop-Gericke, Dmitry Zemlyanov, S Penner, R Schloegl, G Rupprechter, B Kloetzer, N Memmel

Dmitry Yurievich Zemlyanov

Ultrathin PdZn surface alloys on Pd(111) are model systems well-suited for obtaining a microscopic understanding of the mechanisms of Pd/Zn-based catalysis for methanol steam reforming. The temperature-induced compositional and structural changes of these alloy films are investigated in the catalytically relevant temperature range. Heating of multilayer Zn films to 500 K results in the formation of multilayer PdZn alloy films with surface and near-surface composition close to 1:1. In the temperature regime above 550 K the subsurface layers deplete quickly in Zn due to diffusion of Zn atoms into the Pd bulk. In contrast, the composition of the surface layer …

Characterization Of Amino Acid Adlayers On Inas Surfaces Using X-Ray Photoelectron Spectroscopy, John Slavin, Upasana Jarori, Dmitry Zemlyanov, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Removal of surface oxide layers and the prevention of their reformation is an essential step in the use of Ill-V semiconductor technologies. Highlighted here are data exploring the use of amino acid (AA) self-assembled monolayers (SAMs) to block the pre-growth of oxides on indium arsenide surfaces. Three different AAs were used: lysine, aspartic acid, and cysteine. The adlayers were characterized by atomic force microscopy (AFM), Raman, and angle resolved X-ray photoelectron spectroscopy (ARXPS). AFM data suggest that the AA functional groups affect the packing and orientation of the molecules on the surfaces, reinforced by contact angle data. Raman data provide …

Forisome Performance In Artificial Sieve Tubes, Michael Knoblauch, Mike Stubenrauch, Aart J.E. Van Bel, Winfried S. Peters

Winfried S. Peters

Random Lasing In Bone Tissue, Qinghai Song, Shumin Xiao, Zhengbin Xu, Jingjing Liu, Xuanhao Sun, V. Drachev, V. Shalaev, Ozan Akkus, Young Kim

Zhengbin Xu

Owing to the low-loss and high refractive index variations derived from the basic building block of bone structure, we, for the first time to our knowledge, demonstrate coherent random lasing action originated from the bone structure infiltrated with laser dye, revealing that bone tissue is an ideal biological material for random lasing. Our numerical simulation shows that random lasers are extremely sensitive to subtle structural changes even at nanoscales and can potentially be an excellent tool for probing nanoscale structural alterations in real time as a novel spectroscopic modality. (C) 2010 Optical Society of America

Random Laser Spectroscopy For Nanoscale Perturbation Sensing, Qinghai Song, Shumin Xiao, Zhengbin Xu, V. Shalaev, Young Kim

Zhengbin Xu

We report a spectroscopic method using coherent random lasers for a simple, yet nanoscale, sensing approach. Unique spectral properties of coherent random laser emission can be detectably altered when introducing nanoscale perturbations to a simple nanocomposite film that consists of dielectric nanospheres and laser-dye-doped polymer to serve as a transducer. Random lasing action provides a means to amplify subtle perturbations to readily detectable spectral shifts in multiple discrete emission peaks. Owing to several advantages, such as large-area detection, narrow and multiple emission peaks, straightforward detection, and simple fabrication, random laser spectroscopy has the potential for ultrasensitive, yet simple, biosensors in …

Optically Induced Electrokinetic Patterning And Manipulation Of Particles, Stuart Williams, Aloke Kumar, Steven Wereley

Aloke Kumar

The ability to easily and dynamically control fluid mo- tion as well as manipulate particles in suspension is impor- tant for the development and characterization of a variety of lab-on-a-chip processes. Recently, we have introduced an op- tically induced electrokinetic technique termed rapid electro- kinetic patterning (REP) that can rapidly concentrate, trans- late, and pattern colloids of many different sizes and compositions. We have tested polystyrene, latex, and silica beads in sizes ranging from 49 nm to 3.0 um.1,2

Hybrid Opto-Electric Manipulation In Microfluidics-Opportunities And Challenges, Aloke Kumar, Stuart Williams, Han-Sheng Chuang, Nicolas Green, Steven Wereley

Aloke Kumar

Hybrid opto-electric manipulation in microfluidics/nanofluidics refers to a set of methodologies employing optical modulation of electrokinetic schemes to achieve particle or fluid manipulation at the micro-and nano-scale. Over the last decade, a set of methodologies, which differ in their modulation strategy and/or the length scale of operation, have emerged. These techniques offer new opportunities with their dynamic nature, and their ability for parallel operation has created novel applications and devices. Hybrid opto-electric techniques have been utilized to manipulate objects ranging in diversity from millimetre-sized droplets to nano-particles. This review article discusses the underlying principles, applications and future perspectives of various …

Experiments On Opto-Electrically Generated Microfluidic Vortices, Aloke Kumar, Stuart Williams, Steven Wereley

Aloke Kumar

Strong microfluidic vortices are generated when a near-infrared (1,064 nm) laser beam is focused within a microchannel and an alternating current (AC) electric field is simultaneously applied. The electric field is generated from a parallel-plate, indium tin oxide (ITO) electrodes separated by 50 lm. We present the first l-PIV analysis of the flow structure of such vortices. The vortices exhibit a sink-type behavior in the plane normal to the electric field and the flow speeds are characterized as a function of the electric field strength and biasing AC signal frequency. At a constant AC frequency of 100 kHz, the fluid …

All-Spin Logic Device With Inbuilt Nonreciprocity, Srikant Srinivasan, Angik Sarkar, Behtash Behin-Aein, Supriyo Datta

Srikant Srinivasan

The need for low-power alternatives to digital electronic circuits has led to increasing interest in logic devices where information is stored in nanomagnets. This includes both nanomagnetic logic, where information is communicated through magnetic fields of nanomagnets, and all-spin logic (ASL), where information is communicated through spin currents. A key feature needed for logic implementation is nonreciprocity, whereby the output is switched according to the input but not the other way around, thus providing directed information transfer. The objective of this paper is to draw attention to possible ASL-based schemes that utilize the physics of spin-torque to build in nonreciprocity, …