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.

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Short laser pulses interacting with ethylene

 

PNNL: News - Halving hydrogen

PNNL: News - Halving hydrogen

Like a hungry diner ripping open a dinner roll, a fuel cell catalyst that converts hydrogen into electricity must tear open a hydrogen molecule.

Now researchers have captured a view of such a catalyst holding onto the two halves of its hydrogen feast. The view confirms previous hypotheses and provides insight into how to make the catalyst work better for alternative energy uses.

This study is the first time scientists have shown precisely where the hydrogen halves end up in the structure of a molecular catalyst that breaks down hydrogen, the team reported online April 22 in Angewandte Chemie International Edition. 

The design of this catalyst was inspired by the innards of a natural protein called a hydrogenase enzyme.

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Neutron crystallography shows this iron catalyst gripping two hydrogen atoms (red spheres). This arrangement allows an unusual dihydrogen bond to form between the hydrogen atoms (red dots).

Inspired by a music box, Stanford bioengineer creates $5 chemistry set

When Manu Prakash was young he had a thing about flames. He's not encouraging all kids to follow his fiery lead – he did burn one hand pretty badly – but he thinks kids should explore more when it comes to learning about science. That's the idea behind his programmable, toy-like device that won a competition to "reimagine the chemistry set for the 21st century."

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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.

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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

Making the Most of Carbon Nanotube-Liquid Crystal Combos

Dispersions of carbon nanotubes with liquid crystals have attracted much interest because they pave the way for creating new materials with added functionalities. 

Now, a study published in EPJ E by Marina Yakemseva and colleagues at the Nanomaterials Research Institute in Ivanovo, Russia, focuses on the influence of temperature and nanotube concentration on the physical properties of such combined materials. 

These findings could have implications for optimising these combinations for non-display applications, such as sensors or externally stimulated switches, and novel materials that are responsive to electric, magnetic, mechanical or even optical fields.

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Dispersed multi-wall carbon nanotubes on a glass surface. Credit: Yakemseva et al.

How Electrodes Charge and Discharge

The electrochemical reactions inside the porous electrodes of batteries and fuel cells have been described by theorists, but never measured directly. 

Now, a team at MIT has figured out a way to measure the fundamental charge transfer rate — finding some significant surprises.

The study found that the Butler-Volmer (BV) equation, usually used to describe reaction rates in electrodes, is inaccurate, especially at higher voltage levels. 

Instead, a different approach, called Marcus-Hush-Chidsey charge-transfer theory, provides more realistic results — revealing that the limiting step of these reactions is not what had been thought.

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This illustration shows a battery electrode made of lithium iron phosphate (left side of image) coated with carbon, and in contact with an electrolyte material. As the battery is discharged, lithium ions (shown in purple) jump across the coating and insert themselves into the crystal structure, while electrons (shown as circles with minus signs) in the carbon-coating tunnel into the material and attach to iron ions (shown in red). (Phosphate groups are left out of this diagram for clarity.) Illustration courtesy of Peng Bai and Martin Bazant

Energy Breakthrough Uses Sun to Create Solar Energy Materials

In a recent advance in solar energy, researchers have discovered a way to tap the sun not only as a source of power, but also to directly produce the solar energy materials that make this possible.

 

This breakthrough by chemical engineers at Oregon State University could soon reduce the cost of solar energy, speed production processes, use environmentally benign materials, and make the sun almost a “one-stop shop” that produces both the materials for solar devices and the eternal energy to power them.

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