Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chemist shoots chemistry ’in the act’

30.10.2002


A physical chemist at Washington University in St. Louis is combining powerful lasers with clever timing schemes to characterize how chemical reactions occur with very precise atomic and time resolution. Understanding the mechanisms and physics of a chemical reaction at the most fundamental level could provide valuable insights into new directions for the field of chemistry.

Richard A. Loomis, Ph.D., assistant professor of chemistry, is a physical chemist building on the femtochemistry advances of Nobel Prize Winner (1999) Ahmed H. Zewail of Cal Tech who observed chemical bonds breaking as a molecule falls apart in real-time. Loomis’ research group is tackling one of the next major hurdles in chemistry, observing two molecules collide and form reaction products in real-time. These novel efforts are driven by the hopes of understanding how, as Yeats chronicled in the last century, "Things fall apart", and as Loomis now emphasizes, "Things are made."

Loomis discussed his work Oct. 29, 2002, at the 40th New Horizons in Science Briefing, sponsored by the Council for the Advancement of Science Writing, held Oct. 27-30, at Washington University in St. Louis.



Using lasers with extremely short pulse durations and very specific colors, Loomis makes real-time "movies" of molecules forming and then breaking.

"What we’re trying to do is find how molecules prefer to come together to form new compounds, and what forces and geometries encourage the breaking of bonds," Loomis said. "This is a complicated business. We’re trying to learn the road map -- the hills and valleys and winding curves -- that molecules follow during a reaction."

As a physical chemist, Loomis’ research interests are centered on probing and controlling reaction dynamics with atomic resolution -- the most fundamental level. The experiments in the Loomis laboratory uniquely blend a combination of established molecular beam techniques that allow them to cool reactants to the lowest possible temperatures, about -273 degrees Celsius, with sophisticated laser technology which in turn enables them to initiate the reactions with specific energies and preferred orientations at well-defined times.

Simply irresistible, but no energy

At the low temperatures achieved in the experiments, two molecules find each other irresistible and are drawn together. However, they don’t have enough energy to react. "They end up hanging out near each other," Loomis explained. "We trap them in a cluster prior to reaction. This cluster serves as a launching pad from which a laser can be used to excite the molecules at a well-defined time to specific energies and geometries and thus turn the reaction on."

By using multiple lasers, Loomis and his group can not only precisely start the reactions but also monitor the decay of the reactants or the formation of the products using a second laser set to appropriate spectroscopic transitions. At a given delay in time between the first and second laser, a snapshot of the populations of the reactants and products, as well as the relative orientations between the atoms involved in the reaction, can be recorded at that instant along the reaction pathway. By recording numerous snapshots at incrementally increasing delay times between the lasers, a movie of the reaction at the atomic level is generated with sufficient time resolution, less than 0.0000000000001 seconds, to see geometries changing, bonds breaking, and new bonds forming.

As if watching and characterizing chemical reactions isn’t enough, Loomis is also using sophisticated laser pulse-shaping methods and implementing quantum mechanics to control the fate of reactions. Starting with a single ultrashort laser pulse, a computational genetic learning algorithm is used to generate a very complicated pulse sequence that focuses the molecules at desired orientations and energies at a specific time. Such an algorithm derives its behavior from a metaphor of evolution processes in nature. The learning algorithm can be told to enhance the yield of a chemical reaction or to enhance one reaction product over other, undesired reaction products. Loomis emphasizes the utility of this chemistry tool.

"Imagine hitting a key on your computer keyboard and getting one reaction product. Then hit a different key and get a different product without changing anything else, " he said.

The use of lasers to dictate chemistry could actually create entirely new possibilities in chemistry. For instance, it may be possible in the future to simply shine a powerful light with the right properties at just the right time on a bulk mixture of reactants to increase the efficiency of expensive reaction schemes. This could be especially important for industrial chemical production where an increase in a reaction yield of a few percent could mean millions of dollars in profit. Lofty goals, such as improving air quality by blocking the formation of halogen waste products that are formed in combustion and industrial processes, also may be in reach.

Another exciting impact area in which Loomis is striving to make keg contributions is in quantum computing. Here Loomis wants to use the learning algorithm and the carefully tailored laser pulse sequences to quantum mechanically encode information into molecules and materials. He would use the second laser to extract the encoded information from the system at a later time. This aspect of Loomis’ research may make significant impacts on the future of computer design as well as the teleportation or encoded communication of information through space.

Questions

Contact: Gerry Everding, Office of Public Affairs, Washington University in St. Louis, (314) 935-6375; gerry_everding@aismail.wustl.edu

Gerry Everding | EurekAlert!
Further information:
http://news-info.wustl.edu/News/casw/loomis.html

More articles from Life Sciences:

nachricht A blue stoplight to prevent runaway photosynthesis
27.09.2016 | National Institute for Basic Biology

nachricht ‘Missing link’ found in the development of bioelectronic medicines
27.09.2016 | University of Southampton

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

 
Latest News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

The Flexible Grid Involves its Users

27.09.2016 | Information Technology

Process-Integrated Inspection for Ultrasound-Supported Friction Stir Welding of Metal Hybrid-Joints

27.09.2016 | Machine Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>