Nanoimprint lithography patterns with a vertically aligned nanoscale tubular carbon structure

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Youn-Su Kim, Kyeongmi Lee, Jae Suk Lee, Gun Young Jung,

Won Bae Kim. Nanotechnology 2008, 19, 365305.

Purpose:

The authors present a new method using a carbon array as a mold for nanoimprint lithography (NIL) .

Methods:

The carbon array was grown inside a template layer of anodic aluminum oxide (AAO). The AAO exhibits a regularly and vertically alligned pore structure. 1-D carbon structures are then deposited on the surface by thermal chemical vapor deposition. The surface layer is then removed via iron milling, and then the AAO was etched with phosphoric acid.

Key Points:

The method shown enables the fabrication of highly regular, vertically alligned tubular nanostructures for use as molds in nanoimprint lithography. The method is also inexpensive compareed to e-beam and other similar processes. It also could be potentially used in the manufacture of photonic crystals.

Mechanochemical Preparation of Magnetite Nanoparticles by Coprecipitation

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Mechanochemical Preparation of Magnetite Nanoparticles by Coprecipitation

Purpose: This article presents a novel process for preparing magnetite nanoparticles via coprecipitation without the need for surfactant or oxidizing/reducing agents.

Method: Fe₃O₄ nanoparticles were synthesized in a ball mill by first dissolving Iron (III) Chloride in water. The solution was placed in an inert atmosphere and NaOH solution was added. The precipitate formed was then added to a ball mill which was rotated at a rate of 35 rpm. The morphology was then examied with a FE-SEM and EDS. The XRD patterns were also measured with CuKα radiation.

Key Findings: A very simple process to prepare magnetite nanoparticles with high crystallinity in a single step was shown. The ball mill technique increases the reaction rate, while inhibiting particle size. The mechanical nature of the nanoparticle formation implies the possibility of the use of these nanoparticles in the biomedical field.

Laser Pulse Induced Gold Nanoparticle Gratings

Hung, Wen-Chi. Laser Pulse Induced Gold Nanoparticle Gratings. Applied Physics Letters 93, 2008.

Purpose

Synthesis of gold nanoparticle gratings using polarized laser pulses and characterization of their optical diffraction properties.

Methods

A pair Nd-YAG laser was used to produce the gold nanoparticle gratings via spatially periodic laser ablation on a gold thinfilm. The morphology of the gold nanoparticles was then examined using SEM and dark-filed optical microscopy.

Key Findings

1. Morphology is dependant on the fluence of the laser pulse.

2. In the SEM images, a fringe pattern occurs due to localized temperature differences on the gold surface. The higher temperature regions (and brighter bands) result in the formation of the gold nanoparticles. Some nanoparticle formation was observed on the dark stries, though this is probably due to sputtering of adjacent nanoparticles.

3. When a higher fluence laser pulse was used, nanoparticle formation was observed in both light and dark regions of the SEM image. However, the light and dark bands represented areas of high and low concentration, respectively.

4. The diffraction studies revealed that maximum diffraction energies occur at 680 nm and 620 nm for the low and high fluence laser pulses, respectively.

Definition

Nd-YAG laser – yttrium aluminum garnet laser

fluence – number of particles intersecting a unit area

SEM – Scanning Electron Microscope