Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Finely tuned laser strikes the right chord

31.05.2002


Pulses of laser light can make molecules react in ways that are impossible using classical test-tube chemistry. Molecules vibrate, and each molecule has its own “tone,” its own “melody.” It’s a question of finding the right key, and that is something that a “smart” laser beam can do. It can find its way to the right tone. In a new issue of the prestigious journal Nature it is shown how such a laser can be used to control photosynthesis molecules that gather light. This is the first time this feat has been done with such large and complicated molecules. Part of the work has been carried out at the Chemistry Center at Lund University in Sweden.



The experimental work has been performed at the Max Planck Institute for Quantum Optics in Garching, Germany, and researchers from the University of Glasgow and Vrije University in Holland have also been involved. The Lund scientist connected with the project is Dr. Jennifer L. Herek. Research has been under way for years in Lund seeking to understand how the process of photosynthesis, when plants transform sunlight and carbon dioxide into energy, works at the molecular level. One aim among others is to be able to utilize an artificial version of photosynthesis in the future production of energy.

“In our experiments we made use of a complex of antenna molecules, pigments that capture light and pass it on to a reaction center. Without all the knowledge gathered in Lund over the years about this complex, that feat would have been impossible. We could have used guesswork, but we would have had only one chance in a million to get it right,” says Jennifer Herek.


Today it’s possible to study extremely rapid chemical processes with the aid of lasers. At the Section for Chemical Physics, for example, scientists can start a chemical reaction with a laser pulse and then send a new pulse that will bounce back with information about what just happened. This technique has been elaborated by the German research team involved in the project, led by Dr. Marcus Motzkus. It is possible to send several pulses in an extremely short period of time. One pulse registers what is happening; another alters thecourse of the ongoing reaction.

When the laser gets feedback like this about what it has done, it can adapt its pulses to the result and try to find an optimal pulse, the pulse that can bring about the desired reaction in the molecule. In other words, the laser has become “smart.” It is connected to a computer program containing a so-called evolution algorithm. One pulse after another is generated. The “fittest” ones survive and become the “parent generation” of the next series of pulses. In other words, it’s like biological evolution. The color mix, amplitude, time, and a number of different parameters can be adjusted, and the final result can be a whole series of specifically tailored pulses in a certain order.

In order to show that it is possible to control reactions in complicated molecules, researchers must choose something that can be measured in quantifiable terms. Jennifer Herek explains:

“We have worked with an antenna complex in a purple bacterium that uses photosynthesis. Light is captured by carotenoid molecules and transferred to chlorophyll molecules. On the way, half of the energy is lost. For technical reasons, this time we chose to “hamper” nature rather than to “enhance” it. With the aid of lasers, we tried to obstruct this specific transfer more. It turned out to be 30% less effective. We were also able to show that all we influenced was these particular molecules, and nothing else. After having simplified the effective train of pulses, we could show that this was so by shifting the phase of the electric field of neighboring pulses in the train.”

“For a long time we have nurtured the dream that chemists have of being able to control a reaction without the constraints you have to put up with when you have two or more substances reacting with each other,” says Professor Villy Sundström at the Section for Chemical Physics. “With this new method we can learn even more about how photosynthesis works and ultimately be able to apply this knowledge in the creation of artificial photosynthesis.

Göran Frankel | alphagalileo
Further information:
http://www.mpq.mpg.de/lachem/reaction-dynamics/research/LH2/LH2project.html

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

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 evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>