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Articles 1 - 9 of 9
Full-Text Articles in Nanoscience and Nanotechnology
A Study Of Anodization Process During Pore Formation In Nanoporous Alumina Templates, Z. Wu, C. Richter, L. Menon
A Study Of Anodization Process During Pore Formation In Nanoporous Alumina Templates, Z. Wu, C. Richter, L. Menon
Latika Menon
We have carried out a systematic investigation of the anodization procedure in order to determine the exact chemical mechanism of the dissolution process responsible for pore formation in nanoporous alumina templates. We measured the anodization current as a function of time and compared it with the thickness of porous aluminum oxide layer obtained from cross-section scanning electron microscopy images. From this, we calculated the number of moles of electrons generated per mole of porous alumina grown. This analysis is consistent with a reaction mechanism in which aluminum is converted to aluminum oxide in addition with the direct transfer of aluminum …
Size Dependence Of Energetic Properties In Nanowire-Based Energetic Materials, L. Menon, D. Aurongzeb, S. Patibandla, K. Bhargava Ram, C. Richter, A. Sacco
Size Dependence Of Energetic Properties In Nanowire-Based Energetic Materials, L. Menon, D. Aurongzeb, S. Patibandla, K. Bhargava Ram, C. Richter, A. Sacco
Latika Menon
We prepared nanowire-array-based thin film energetic nanocomposites based on Al–Fe₂O₃. The ignition properties as a function of wire dimensions and interwire spacing have been investigated. We show significant variations in ignition behavior, which we relate to the kinetic and heat transfer dynamics of the various configurations studied. Our results indicate the possibility for nanoscale control of reaction parameters such as flame temperature and burn rate in such composites for optimized configurations (optimum wire size, interwire spacing, film thickness, etc.).
Possible Room-Temperature Ferromagnetism In Hydrogenated Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Yung Joon Jung, Don Heiman, Evan Glaser, Latika Menon
Possible Room-Temperature Ferromagnetism In Hydrogenated Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Yung Joon Jung, Don Heiman, Evan Glaser, Latika Menon
Latika Menon
We find that ferromagnetism can be induced in carbon nanotubes (CNTs) by introducing hydrogen. Multiwalled CNTs grown inside porous alumina templates contain a large density of defects resulting in significant hydrogen uptake when annealed at high temperatures. This hydrogen incorporation produces H-complex and adatom magnetism which generates a sizable ferromagnetic moment and a Curie temperature near TC=1000 K. We studied the conditions for the incorporation of hydrogen, the temperature-dependent magnetic behavior, and the dependence of the ferromagnetism on the size of the nanotubes.
Optimal Parameters For Synthesis Of Magnetic Nanowires In Porous Alumina Templates: Electrodeposition Study, Adam L. Friedman, Latika Menon
Optimal Parameters For Synthesis Of Magnetic Nanowires In Porous Alumina Templates: Electrodeposition Study, Adam L. Friedman, Latika Menon
Latika Menon
We have carried out a systematic study of the electrodeposition process to understand the effect of varying three important quantities on the synthesis of nanowires inside porous alumina templates. We have electrodeposited iron nanowires inside porous alumina to determine the optimal settings of these variables to induce effective and efficient nanowire growth. First, we vary the pH of the electrolyte solution to show that pH has little effect on the deposition rate. Second, we vary the magnitude of the applied ac voltage to show that the deposition rate increases with increasing voltage. Finally, we vary the frequency of the applied …
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Latika Menon
Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.
Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. P. Bennett, L. Menon, D. Heiman
Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. P. Bennett, L. Menon, D. Heiman
Latika Menon
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.
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. D. F. Casse, W. T. Lu, Y. J. Huang, E. Gultepe, L. Menon, S. Sridhar
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. D. F. Casse, W. T. Lu, Y. J. Huang, E. Gultepe, L. Menon, S. Sridhar
Latika Menon
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 …
A Study Of Titania Nanotube Synthesis In Chloride-Ion-Containing Media, E. Panaitescu, C. Richter, L. Menon
A Study Of Titania Nanotube Synthesis In Chloride-Ion-Containing Media, E. Panaitescu, C. Richter, L. Menon
Latika Menon
We have completed a detailed experimental investigation into the recently discovered synthesis of titania nanotubes in chloride-ion-containing media. We show that the role of the chloride ions is catalytic and it has a strong effect in increasing the reactivity of the solution, while the nature of cations has no visible role. We have identified the critical parameters for optimal growth and fast production of nanotubes, and a basic growth mechanism for the tubes is proposed. This opens routes for significant improvements of the method toward uniformity and/or better overall yield, making it a viable alternative to the present established methods.
Growth And Magnetic Properties Of Polycrystalline Self-Assembled Bifurcated Co Nanowires, Jesse Silverberg, Adam L. Friedman, Latika Menon
Growth And Magnetic Properties Of Polycrystalline Self-Assembled Bifurcated Co Nanowires, Jesse Silverberg, Adam L. Friedman, Latika Menon
Latika Menon
We use anodization of aluminum foil with variable applied anodization voltage to create an alumina template with bifurcated porous structures. The template is then used to electrodeposit Co, fabricating unique bifurcated Co nanowires. In order to better understand the crystal structure of our new material, we then report magnetic properties of these self-assembled bifurcated Co nanowires. Magnetic measurements of the bifurcated wires are studied as functions of branch/stem ratios, wire length, and temperature. The results are compared with those of straight Co nanowires of similar dimensions and thin film Co samples to find that a different crystal lattice structure prevails …