FW: Watch "Nanowires and Nanocrystals for Nanotechnology"

Nanowires and Nanocrystals for Nanotechnology

42 min 15 sec - Sep 12, 2006
Average rating:   (126 ratings)
Description: Google Tech Talks September 12, 2006 Yi Cui is an assistant professor in the Materials Science and Engineering Department at Stanford University. He is a recipient of the Technology Review World Top 100 Young Innovator Award. He received his PhD degree from Harvard University working with Prof. Charles Lieber. He received his B.S. degree from Univ of Science and Technology of China. ABSTRACT Nanowires and nanocrystals represent important nanomaterials with one-dimensional and zero-dimensional morphology, respectively. Here I will give an overview on the research about how these nanomaterials impact the critical applications in faster transistors, smaller nonvolatile memory devices, efficient solar energy conversion, high-energy battery and nanobiotechnology.

Want to see more cool videos?
Go to video.google.com/

Think you have an even cooler video?
Add it at video.google.com/videouploadform

If you're having trouble watching the video, try copying the following URL into your browser:
http://video.google.com/videoplay?docid=6571968052542741458&subtitle=on&pr=goog-sl

The Nanostructure Problem

Nanostructures can pose big measurement problems:
While many methods exist for probing the atomic structure on the nanoscale, no single technique can provide a unique structural solution. This paper calls for a coordinated effort by researchers to develop a coherent strategy for a comprehensive solution of the “nanostructure problem” using inputs from multiple experimental methods and theory.

###

* S.J.L. Billinge and I. Levin. The problem with determining atomic structure at the nanoscale. Science, 316: 5823, April 27, 2007.

Today's Updates

Researchers 'see' catalyst molecules at work: Researchers have for the first time 'watched' in real time single molecules of catalyst participating in a reaction at a solid-liquid interface

Instant insight: Nanocrystals as sensors: This article address the paradox around quantum dots... the properties of the quantum dots for imaging and labeling applications are achieved by making the quantum dot impervious to its environment. How can quantum dots be sensitive to their environment if they are encased within the cocoon of a passivating overcoat?

Nanoscale scales: Scientists at the Massachusetts Institute of Technology (MIT) in the US have designed a device able to accurately weigh to within one femtogram (one thousandth of a millionth of a millionth or 10-15 of a gram) single nanoparticles within a liquid.

Water's surface is acidic: Pure, neutral water has an acid skin. This striking notion has now been confirmed by calculations and tests.The finding could be significant for a number of disciplines. In atmospheric chemistry, many important chemical reactions between trace gases take place at the surface of water droplets in clouds where pH is an essential factor and low pH could also affect the rates of carbon dioxide absorption at the ocean surface. In molecular biology the effect might be reproduced where water comes into contact with water-repelling (hydrophobic) parts of proteins, changing the acid-base chemistry.

Determination of Size and Concentration of Gold Nanoparticles from UV-Vis Spectra: Work by Wolfgang Haiss et al. provide a simple and fast method to determine size and concentration of nanoparticles. Their work, published in Analytical Chemistry describe the theoretical analysis on the dependence of the optical properties of spherical gold nanoparticles on particle size and wavelength using multipole scattering theory, where the complex refractive index of gold was corrected for the effect of a reduced mean free path of the conduction electrons in small particles. The theoretical results were compared to experimental data; gold nanoparticles in the size range of 5 to 100 nm were synthesized and characterized with TEM and UV-vis. Excellent agreement was found, showing that the data produced here can be used to determine both size and concentration of gold nanoparticles directly from UV-Vis spectra. Equations for this purpose are derived, and the precision of various methods is discussed.

Scanning magnetoresistance microscopy

Scanning magnetoresistance microscopy of atom chips
Results highlight the use of scanning MR microscopy as a convenient and powerful technique for precisely characterizing the magnetic fields produced near the surface of atom chips.

News: IBM researchers push MRI imaging to nanoscale

Researchers at IBM’s Almaden Research Center have developed magnetic resonance imaging (MRI) techniques to visualize nanoscale objects. The new techniques are a major milestone in the quest to build a microscope that could "see" individual atoms in three dimensions.

Click here to go to the IBM news website

A Peek Inside*

The semiconductor industry routinely fabricates device structures with feature sizes smaller than 100 nm. With millions of components crowded onto each chip and complex circuitry arrayed in three dimensions, methods to test the structures for defects--preferably nondestructively and with high throughput--become challenging. Techniques for imaging the subsurface structures tend to face a tradeoff between resolution and contrast. The probe light must have a relatively long wavelength (usually in the infrared) in order to penetrate through several millimeters of silicon in the wafer and be absorbed by the active layers of the device; however, this wavelength requirement has generally restricted lateral resolution. Ramsay et al. combine immersion lens imaging with two-photon absorption microscopy to improve both the lateral resolution and the absorption contrast, thereby providing a technique for the high-resolution three-dimensional imaging of the subsurface structures in silicon chip circuitry. -- ISO

Appl. Phys. Lett. 90, 131101 (2007).

*the above text is taken directly from - this link: http://www.sciencemag.org/content/vol316/issue5822/twil.dtl?rss=1#316/5822/174b