Trestles CW/fs laser for carbon nanotubes spectroscopy and photophysics research at Rice University

Del Mar Photonics featured customer Bruce Weisman. Professor Weisman ordered Trestles Ti:Sapphire laser with built-in DPSS pump laser. dmphotonics.com Professor Weisman wrote: Our applications are for carbon nanotube excitation, mostly with a cw beam but in some experiments with mode-locked pulses. Del Mar Photonics offered Trestles Ti:Sapphire model with both CW and femtosecond modes of operation. R. Bruce Weisman Professor of Chemistry Research Statement Dr. R. Bruce Weisman and his group investigate the spectroscopy and photophysics of fullerenes and carbon nanotubes. All of these are closed nanoscopic structures formed from carbon atoms. Fullerenes, such as C60, C70, and their chemical derivatives, have unusual molecular properties that cause interesting behaviors following the absorption of light. Time-resolved absorption and emission methods are used to study radiationless decay, photochemical reactions, and energy transfer in fullerenes. Another major research topic is single-walled carbon nanotube spectroscopy. Following the discovery in Weisman?s lab of near-infrared nanotube fluorescence, the group has measured and unraveled the absorption and emission spectra of more than 30 semiconducting nanotube species. Follow-up projects include detailed elucidation of nanotube electronic structure, as well as applications in non-invasive biomedical imaging and analytical nanotechnology. Selected Publications R. Bruce Weisman and Shekhar Subramoney “Carbon Nanotubes …
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Study Uncovers Mesothelioma Link to Nanotechnology

Study Uncovers Mesothelioma Link to Nanotechnology

Mesothelioma has long been linked to the inhalation and exposure to asbestos fibers and dust, so when scientists uncovered an additional potential cause for this incurable form of lung cancer, the unthinkable became a reality.

According to researchers based out of the Woodrow Wilson International Centre for Scholars in Washington D.C., the early 90′s development of carbon nanotubes has been an amazing feat for technological applications, however, it has not gone without its price. Specifically, carbon nanotubes may be causing harm to the human body in the form of mesothelioma cancer.

If the carbon nanotubes are introduced into the wrong environment, the development of lesions and inflammation of the lungs occurs – symptoms similar to that of mesothelioma cancer and asbestos exposure. Researchers uncovered the finding through exposure of carbon nanotubes to animals.

Dr. Andrew Maynard, who published a study in the journal Nature Nanotechnology, described the use of nanotubes and the potential link to mesothelioma cancer. He said that currently, nanotubes are being implemented because of their awesome abilities at conducting heat and electricity. Mostly, Dr. Maynard explains, the nanotubes are being implemented into sports equipment. He said that there are no regulations as to where nanotubes can be implemented and there are currently no requirements for the use of nanotubes to be disclosed to the general public.

What Are Nanotubes?

According to Maynard, nanotubes are a product of nanotechnology research, one he considers the “poster child” of nanotechnology. The nanotubes are cylindrical structures comprised of carbon atoms that have been rolled together. Maynard’s study found that when mice were exposed to nanotubes, they developed asbestos-induced symptoms within the lungs. While he and other researchers consider nanotubes to be safe – when encased – the risk occurs when nanotubes are incinerated or broken.

Nanotubes are currently being used in:

* a variety of sports equipment

* bicycle frames

* tennis rackets

* electronic gas detectors

* radios

Additionally, because of the strength of nanotubes, many consider its future use to vastly effect several business ventures and areas, and be widely used in industries including:

* aerospace

* automobile

* airplanes

* television box productions

* medical

* environmental uses

Working with Nanotubes

While the National Institute for Occupational Safety and Health (NIOSH) is doing research on nanotoxicology, there is little knowledge or research currently available regarding the safety of using nanotechnology. Additionally, Dr. Maynard noted that because of the ever-increasing nanotechnology industry, which is likely to be worth .6 trillion by 2014, it will be difficult to adequately and accurately assess nanotechnology safety because of the technology’s quick growth, which is also being used in the food industry.

Transparency of nanotoxicology among some nanotechnologically-produced products may fall into the hands of manufacturers and producers, which John M. Balbus, health program chief for the Environmental Defense Fund who was interviewed in a Washington Post article on nanotechnology, said could either be a very good thing with open communications, or a very bad thing replicating the mistakes made among the construction industry’s use of asbestos. However, he noted that upfront communication regarding the dangers of nanotechnology with the public may increase because of the previous mistakes made by other industries in hiding mesothelioma conditions from the public.

Finding Help with Nanotube

Fujitsu Laboratories New Carbon Nanotube Composite : DigInfo

DigInfo – (movie.diginfo.tv) Fujitsu Laboratories has made a breakthrough in carbon nanotube research. The company has combined carbon nanotubes and graphene, both of which are nano-scale carbon structures, to self-form a new nano-scale carbon composite, at the relatively low temperature of 510 degrees Celsius. Graphene is a honeycomb crystal lattice of carbon atoms. In experiments using chemical vapor deposition, a technique to synthesize thin films and structures on a substrate by thermally decomposing a feedstock gas in a vacuum chamber, Fujitsu Labs discovered that several to dozens of layers of graphene were formed self-organizingly on the vertically aligned multi-walled carbon nanotubes in such a way that they are connected perpendicularly. It is known that carbon nanotubes are linear, one-dimensional structures, and therefore they nearly lack thermal or electrical conductivity between tubes in the two-dimensional directions perpendicular to the tube axis. As attention has been paid to heat, how to increase heat radiation is becoming an important issue. The carbon nanotube composite is expected to be a material with high heat radiation capability. Since graphite flows electrons very smoothly, it can also function as a semiconductor. As an electronics company, Fujitsu Labs aims to use the new structure to improve today’s LSI performance by applying it to dealing with LSI heat radiation and using it in transistors.
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What is Nanotube?

By Najib Altawell

They were discovered in 1991 by the Japanese electron microscopist Simio Iijima who was studying the material deposited on the cathode during the arc-evaporation synthesis of fullerenes. Carbon nanotubes are fullerene-related structures which consist of graphene[1] cylinders closed at either end with caps containing pentagonal rings. Examples of Nanotubes are Single-layer nanotubes and nanotube “ropes” and nanohorns. Carbon nanotubes, therefore, are rolled-up sheets of graphite – i.e. the same material that is used in pencils. A sheet of graphite is composed of carbon atoms arranged in a flat hexagonal pattern similar to chicken wire mesh.

Nanoelectronic has witnessed a shift towards molecular systems in recent years. Though the term molecular electronic is rather an old one, it is only recently that single molecules have become the focus of interest, as nanoelectronic start to surface. This was triggered by research on carbon nanotubes. But before the carbon nanotubes entered the scene, molecular electronic was the science of organic polymers, their synthesis, processing and doping. With carbon nanotubes, we finally have a model system at hand that is equally of interest for chemists, material scientists and physicists. However, carbon nanotubes are supramolecular objects for a chemist; they are one-dimensional solids for a physicist. In the future, more of this supramolecular structure will be studied on a single molecule level.

Theorists have shown that nanotubes can be conducting or insulating depending on their structure. Therefore, this may lead to applications in nanoelectronic.

Wires are not possible for use in nanoelectronic, because they are susceptible to thinning and breakage. Despite recent interest in carbon nanotubes, they have variable electronic properties, depending on their orientation, reducing their functionality as electrical conductors.

One problem that plagues researchers looking to fashion circuit components from nanotubes is separating metallic tubes from the ones that are semi-conducting. Common synthesis procedures produce spaghetti-like mixtures of nanotube ropes that are unusable for semiconductor applications because they contain both types of tubes.

Nanotubes can be metals or semiconductors, and because of their strong chemical bonds and satisfied valences[2], the materials boast high thermal, mechanical, and chemical stability. In addition, carbon nanotubes can be efficient conductors as a result of their tiny diameters, long lengths, and defect-free structures that make them ideal one-dimensional systems.

Theoretical models have predicted that nanotubes could behave as ideal one-dimensional “quantum wires” with either semi conducting or metallic behaviours. Study of Transmission Electron Micrograph (TEM) images, however, has indicated that the nanotubes also incorporate kinks and defects into their walls

Progress in nanotubes synthesis has now yielded single-walled nanotubes (SWNTs) with well-defined diameters, bringing the experimental situation much closer to that of the theoretical models. Recent measurements indicate that these materials do behave like one-dimensional wires. The SWNTs should also be more sensitive to defects, to the extent that defects may dominate the transport characteristics. In this work, an STM tip was used as a sliding electrical contact to probe the length-dependence of SWNT conductance. Although atomic defects were not directly imaged, sharp conductance transitions and hetero-junction behaviours in the nanotube conductance are suggestive of the signatures of nanotube defects.

Altawell.

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