Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seeing molecules move in real-time

23.03.2009
Ultrafast lasers instantaneously track a molecular twist in progress

“Watching chemical reactions in real-time has long been a dream of chemists,” says Tahei Tahara of RIKEN’s Advanced Science Institute in Wako. “To reach a correct understanding of chemical reactions, this ‘watching’ is crucial.”

Tracking atoms in chemical reactions has previously seemed unrealistic, because the nuclei move so fast—movements can be complete within 1 picosecond (10-12 second). However, thanks to Tahara, scientists are awakening to a reality where an atom can be followed along a three-dimensional path.

In 2003, Tahara and his colleagues applied the technique known as impulsive stimulated Raman spectroscopy to measure short-lived, excited-state molecules for the first time (1). Using this method, the researchers initiated a chemical reaction by exciting electrons. Then, they induced the entire molecule to vibrate using 10-femtosecond (10-14 second) lasers—which emit light faster than nuclei move. Finally, using a third laser pulse, they measured how these atoms vibrated as the reaction progressed.

Now Tahara and a team of international and Japanese scientists have directly observed how an organic molecule named stilbene rearranges its structure (2). The initial isomer, called cis-stilbene, has two benzene rings positioned close together and connected by a carbon double bond. When excited by light, this molecule twists and rearranges to trans-stilbene, such that the benzene rings end up far apart.

Scientists have long believed that stilbene rearrangement is accomplished by the large motion of the benzene rings. Watching this reaction with Tahara’s spectroscopic method, however, revealed that the molecule changes geometry using a completely different mechanism.

“With excitation, the central carbon double bond is weakened,” explains Tahara. Then, hydrogen atoms attached to the carbon double bond moved in opposite directions, initiating a twisting motion that led to trans-stilbene. “That stilbene twisting is realized by hydrogen atom movement, [and] not by a large motion of benzene rings, was surprising to us,” says Tahara.

To visualize the three-dimensional molecular motion, the team combined experimental results with a high-level quantum-chemical calculation. The computation correlated the frequency changes observed in the experiment with particular molecular movements—and helped identify the exact twisting mechanism.

Tahara and his team’s advanced spectroscopy provides reliable checkpoints to gauge the accuracy of theoretical calculations—a combined approach that will be useful in visualizing other molecular systems.

Tahara says he doesn’t know how conceivable it is to control chemical reactions by light. “Nevertheless, I would like to try it on the basis of solid understanding of the potential energy of reactive molecules, which is obtainable by this type of study.”

References:

1. Fujiyoshi, S., Takeuchi, S. & Tahara, T. Time-resolved impulsive stimulated Raman scattering from excited-state polyatomic molecules in solution. Journal of Physical Chemistry A 107, 494–500 (2003).

2. Takeuchi, S., Ruhman, S., Tsuneda, T., Chiba M., Taketsugu T. & Tahara, T. Spectroscopic tracking of structural evolution in ultrafast stilbene photoisomerization. Science 322, 1073–1077 (2008).

The corresponding author for this highlight is based at the RIKEN Molecular Spectroscopy Laboratory

Saeko Okada | Research asia research news
Further information:
http://www.researchsea.com
http://www.rikenresearch.riken.jp/research/667/

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>