Steering Chemical Reactions with Laser Pulses

Usually, chemical reactions just take their course, much like a ball rolling downhill. 

However, it is also possible to deliberately control chemical reactions: at the Vienna University of Technology, molecules are hit with femtosecond laser pulses, changing the distribution of electrons in the molecule.  

This interaction is so short that at first it does not have any discernable influence on the atomic nuclei, which have much more mass than the electrons. However, the disturbance of the electron distribution can still initiate chemical processes and eventually separate the nuclei from each other. 

The properties of the laser pulse determine which chemical final products are created.

Read more here... 

Short laser pulses interacting with ethylene

 

Fighting cancer with lasers and nanoballoons that pop

Chemotherapeutic drugs excel at fighting cancer, but they’re not so efficient at getting where they need to go.

They often interact with blood, bone marrow and other healthy bodily systems. This dilutes the drugs and causes unwanted side effects.

Now, researchers are developing a better delivery method by encapsulating the drugs in nanoballoons – which are tiny modified liposomes that, upon being struck by a red laser, pop open and deliver concentrated doses of medicine.

Read more here...

The image shows a nanoballoon before (left) and after (right) being hit by a red laser. The laser causes the balloon to pop open and release the anti-cancer drugs directly at a tumor. Credit: Jonathan Lovell

Revolutionary Solar Cells Double as Lasers

Revolutionary solar cells double as lasers

Commercial silicon-based solar cells - such as those seen on the roofs of houses across the country - operate at about 20% efficiency for converting the Sun’s rays into electrical energy. It’s taken over 20 years to achieve that rate of efficiency.

A relatively new type of solar cell based on a perovskite material - named for scientist Lev Perovski, who first discovered materials with this structure in the Ural Mountains in the 19th century - was recently pioneered by an Oxford research team led by Professor Henry Snaith. 

Read more here...

New Technique Makes LEDs Brighter, More Resilient

New Technique Makes LEDs Brighter, More Resilient

 “By coating polar GaN with a self-assembling layer of phosphonic groups, we were able to increase luminescence without increasing energy input,” says Stewart Wilkins, a Ph.D. student at NC State and lead author of a paper describing the work. “The phosphonic groups also improve stability, making the GaN less likely to degrade in solution.

Scientists open a new window into quantum physics with superconductivity in LEDs

A team of University of Toronto physicists led by Alex Hayat has proposed a novel and efficient way to leverage the strange quantum physics phenomenon known as entanglement. 

The approach would involve combining light-emitting diodes (LEDs) with a superconductor to generate entangled photons and could open up a rich spectrum of new physics as well as devices for quantum technologies, including quantum computers and quantum communication. 

Read more here...

A Molecular Ballet under the X-ray Laser

An international team of researchers has used the world’s most powerful X-ray laser to take snapshots of free molecules. 

The research team headed by Prof. Jochen Küpper of the Hamburg Center for Free-Electron Laser Science (CFEL) choreographed a kind of molecular ballet in the X-ray beam. 

With this work, the researchers have cleared important hurdles on the way to X-ray images of individual molecules, as they explain in the scientific journal Physical Review Letters. 

CFEL is a cooperation of DESY, the University of Hamburg, and the Max Planck Society.

Read more here...

The molecules (green stream) enter the test chamber with random orientation and are forced to all take up the same pose by an optical laser (red). A bright X-ray flash (blue) produces a diffraction image (upper right) that contains structural information about the molecule. Credit: Stephan Stern/CFEL

 

Leeds Researchers Build World’s Most Powerful Terahertz Laser Chip

University of Leeds researchers have taken the lead in the race to build the world’s most powerful terahertz laser chip. 

 

A paper in the Institution of Engineering and Technology’s (IET) journal Electronics Letters reports that the Leeds team has exceeded a 1 Watt output power from a quantum cascade terahertz laser.

Read more here...

Credit: University of Leeds

Superconductivity in Orbit: Scientists Find New Path to Loss-Free Electricity

Armed with just the right atomic arrangements, superconductors allow electricity to flow without loss and radically enhance energy generation, delivery, and storage. 

Scientists tweak these superconductor recipes by swapping out elements or manipulating the valence electrons in an atom's outermost orbital shell to strike the perfect conductive balance. 

Most high-temperature superconductors contain atoms with only one orbital impacting performance—but what about mixing those elements with more complex configurations?

Now, researchers at the U.S. Department of Energy's Brookhaven National Laboratory have combined atoms with multiple orbitals and precisely pinned down their electron distributions. 

Read more here...

These images show the distribution of the valence electrons in the samples explored by the Brookhaven Lab collaboration—both feature a central iron layer sandwiched between arsenic atoms. The tiny red clouds (more electrons) in the undoped sample on the left (BaFe2As2) reveal the weak charge quadrupole of the iron atom, while the blue clouds (fewer electrons) around the outer arsenic ions show weak polarization. The superconducting sample on the right (doped with cobalt atoms), however, exhibits a strong quadrupole in the center and the pronounced polarization of the arsenic atoms, as evidenced by the large, red balloons. Credit: Brookhaven Lab scientists and study coauthors Lijun Wu, Yimei Zhu, Chris Homes, and Weiguo Yin

Diamond Defect Boosts Quantum Technology

New research shows that a remarkable defect in synthetic diamond produced by chemical vapor deposition allows researchers to measure, witness, and potentially manipulate electrons in a manner that could lead to new “quantum technology” for information processing. The study is published in the January 31, 2014, issue of Physical Review Letters.

 

Normal computers process bits, the fundamental ones and zeros, one at a time. But in quantum computing, a “qubit” can be a one or a zero at the same time.

This duplicitous state can allow multitasking at an astounding rate, which could exponentially increase the computing capacity of a tiny, tiny machine.

Read more here...

Credit: carnegiescience.edu

Graphene-Based Field-Effect Transistor With Semiconducting Nature Opens Up Practical Use in Electronics

UNIST announced a method for the mass production of boron/nitrogen co-doped graphene nanoplatelets, which led to the fabrication of a graphene-based field-effect transistor (FET) with semiconducting nature. This opens up opportunities for practical use in electronic devices. 

The Ulsan National Institute of Science and Technology (UNIST) research team led by Prof. Jong-Beom Baek have discovered an efficient method for the mass production of boron/nitrogen co-doped graphene nanoplatelets (BCN-graphene) via a simple solvothermal reaction of BBr3/CCl4/N2 in the presence of potassium. This work was published in “Angewandte Chemie International Edition” as a VIP (“Very Important Paper”).

Read more

A schematic representation for the formation of BCN-graphene via solvothermal reaction between carbon tetrachloride (CCl4) boron tribromide (BBr3) and nitrogen (N2) in the presence of potassium (K). Photograph is of the autoclave after the reaction, showing the formation of BCN-graphene (black) and potassium halide (KCl and KBr, white).

 

Metamaterials offer route to room-temperature superconductivity

Metamaterials offer route to room-temperature superconductivity

A new way of making high-temperature superconductors that is based on metamaterials has been proposed by physicists in the US. Their plan involves combining a low-temperature superconductor with a dielectric material to create a metamaterial that is a superconductor at much higher temperatures than its constituent materials. The team is now looking at testing its proposal in the lab and is hopeful that its work could offer a route to creating a superconductor that operates at room temperature.

Metamaterial superconductors at liquid nitrogen temperatures?