Byline: Kenneth Turner, Jason Campbell, Emma Tevaarwerk, Venkat Chandrasekhar, R.P.H. Chang, Nathan Unterman, and Marcel Grdinic Photo by Nathan Unterman Nanoscience is an extremely relevant topic for today's students. By 2015 it is estimated that 3 million workers will be needed in the nanotech industry (Roco 2002). Nano terms have already infiltrated our daily culture. For example, nano items have appeared in Star Trek and Batman cartoons; the popular Richard Crichton book Prey features nanobots; and many students have Apple's iPod nano (you may have to correct a misconception if students think that the iPod nano is the size of a nanometer.) Furthermore, products that incorporate nanotechnology are already in the marketplace. Nano-Tex fabric, engineered to mimic the fuzz on a peach, features billions of tiny nanowhiskers that force water to bead up and roll off clothing. Carbon-nanotube reinforced tennis racquets are lighter and stronger than conventional racquets, while nano-composite containing tennis balls last longer than conventional products. Ten carbon atoms linked one after another compose roughly a nanometer-so the nanoworld is not quite the same size of atoms, but it is close. The nanoworld is literally not big enough to behave as bulk matter and not small enough to behave as individual atoms. Conventional bulk models fail us, as do atomic ones. This ambiguity leads to a variety of unique and potentially useful mechanical, optical, magnetic, electrical, chemical, thermal, and biological properties of nanoscale materials. Since nano refers to anything nanosized regardless of elemental composition, nanoscience and technology encompasses all areas of science and engineering. Nanoscience refers to the fundamental study of scientific phenomena, which occur at the nanoscale-nanotechnology to the exploitation of novel properties and functions of materials in the sub-100 nm size range (NNI 2006). One of the underlying principles of science is development of models of observed phenomena. In biology, the Hardy-Weinberg principle is a model for predicting alleles. In physics, a particle subject to constant net force is a model in mechanics that governs bidirectional and projectile motion. In chemistry, the particle model for gasses has been used to explain gas behavior. As science teachers, we look for innovative ways to bring a model and its corresponding representations to our students. A concrete and perhaps even tangible representation helps students grasp complex relationships and construct new knowledge. As students are increasing their abilities to understand abstract concepts, it helps them if we can provide some concrete modeling. Such activities help students build their understanding through laboratory experiences and concept construction. Fortunately for science teachers, the same lens that brings clarity to other aspects of the world around us can bring nanoscience into focus as well: the use of macroscopic representations to simplify and explain. To that end, the National Center for Learning and Teaching Nanotechnology (NCLT) based at Northwestern University is developing materials to bring nanoscience into the classroom. These materials center around key new concepts in nanoscience, including surface-area-to-volume ratio and the dependence of the nature and properties of matter on size. In this article, we discuss nanoconcept materials developed around a key measurement device of nanoscience, the scanning probe microscope (SPM). Seeing by feeling Traditionally, looking at something small means looking at the object with an optical microscope. However, the size of objects easily resolved with an optical microscope is limited by diffraction to roughly 200 nm. The SPM is like a tiny finger, dragged across the nanolandscape, capable of atomic level resolutions. Just as a student could drag their finger across a surface and tell if it was rough or smooth, hot or cold, firm or gel-like, so the probe of the SPM can be used to tell much about nanosurface characteristics. …
X‐ray absorption spectroscopy technique is used to study copper‐doped ZnO thin films, prepared by pulsed‐laser deposition. The samples with various doping levels are examined. It is found that the samples contain metallic clusters with the sizes ⩽ 2 nm as well as Cu1+ and Cu2+ states. The Cu1+ states exist as stable oxide clusters, while the Cu2+ ones participate in the ZnO lattice some of which may be pertaining to the surfaces of the Cu clusters as well. The copper clusters of ∼1 nm are unstable and fragment under monochromatic x‐ray beam illumination.
Spectroscopic ellipsometry (SE) has been used to determine the complex pseudo dielectric functions, ε1(E)+iε2(E), of ZnO films on (0001) Al2O3 substrates over the spectral range of 1.33 and 4.96 eV at room temperature. The SE measurements are carried out with E⊥c at angles of incidence of 60° and 65° with respect to the surface normal. Below the band gap, the refractive index n is found to follow the first order Sellmeir dispersion relationship n2(λ)=1+1.881λ2/(λ2−0.05382). A free excitonic structure located at the band edge of 3.32 eV is clearly observed in the pseudo absorption spectrum. Elliott expression with Lorentzian broadening is used to model the pseudo absorption coefficient above the band edge.
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