Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breaking the bond: To take part or not?

09.07.2018

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 compounds or for biomolecules in solution and is therefore of great industrial importance.


In a specially constructed experiment, the physicists from Innsbruck collide the charged particles with molecules in vacuum and examine the reaction products.

The Royal Society of Chemistry

In this reaction, charged particles encounter molecules and one molecular group is replaced by another. For a long time, science has been trying to reproduce these processes at the interface of chemistry and physics in the laboratory and to understand them at the atomic level.

The team headed by experimental physicist Roland Wester at the Institute of Ion Physics and Applied Physics at the University of Innsbruck is one of the world's leading research groups in this field.

Proton Exchange Reaction Strengthened

In a specially constructed experiment, the physicists from Innsbruck collide the charged particles with molecules in vacuum and examine the reaction products. To determine if targeted vibration excitation has an impact on a chemical reaction, the scientists use a laser beam that excites a vibration in the molecule. In the current experiment, negatively charged fluorine ions (F-) and methyl iodide molecules (CH3I) were used.

In the collision, due to the exchange of an iodine bond with a fluorine bond, a methyl fluoride molecule and a negatively charged iodine ion are formed. Before the particles meet, the laser excites carbon-hydrogen stretching vibrations in the molecule. "Our measurements show that the laser excitation does not enhance the exchange reaction," says participating scientist Jennifer Meyer. "The hydrogen atoms just seem to be watching the reaction."

The result is substantiated by the observation that a competing reaction strongly increases. In this other proton exchange reaction, a hydrogen atom is torn from the methyl iodide molecule and hydrogen fluoride (HF) is formed. "We let the two species collide 20 times per second, the laser is applied in every second collision, and we repeat the process millions of times," explains Meyer.

“Whenever the laser is irradiated, this proton exchange reaction is drastically amplified." Theoretical chemists from the University of Szeged in Hungary and the University of New Mexico in the USA have further supported the experimental results from Innsbruck using computer simulations.

Spectator Role in Focus

In high-precision investigations of chemical processes, only the simplest model, the reaction of an atom with a diatomic molecule, has so far been studied. "Here, all particles are inevitably involved in the reaction. There are no observers", says Roland Wester. The system that we are now studying is so large that observers appear. However it is still small enough to be able to study these observers very precisely." For large molecules, there are many particles that are not directly involved in the reaction. The investigation of their role is one of the long-term goals of the Wester group. The researchers also want to refine the current experiment in order to uncover further possible subtle effects.

Laser Controlled Chemistry

The question of whether certain reactions can be intensified by the targeted excitation of individual molecular groups is also an important consideration. "If you understand something, you can also exercise control," sums up Roland Wester. "Instead of stimulating a reaction through heat, it may make sense to stimulate only individual groups of molecules to achieve a specific reaction," adds Jennifer Meyer. This may avoid competing reaction processes that are a common problem in industrial chemistry or biomedical research. The more precise the control over the chemical reaction, the less waste is produced and the lower the costs.

The current paper has been published in the journal Science Advances. The research was funded by, among others, the Austrian Science Fund FWF and the Austrian Academy of Sciences.

Publication: Stretching vibration is spectator in nucleophilic substitution. Martin Stei, Eduardo Carrascosa, Alexander Doerfler, Jennifer Meyer, Balázs Olasz, Gábor Czakó, Anyang Li, Hua Guo, Roland Wester. Science Advances 2018 (Open Access) DOI: 10.1126/sciadv.aas9544

Weitere Informationen:

http://dx.doi.org/10.1126/sciadv.aas9544 - Stretching vibration is spectator in nucleophilic substitution. Martin Stei, Eduardo Carrascosa, Alexander Doerfler, Jennifer Meyer, Balázs Olasz, Gábor Czakó, Anyang Li, Hua Guo, Roland Wester. Science Advances 2018 (Open Access) DOI: 10.1126/sciadv.aas9544
https://www.uibk.ac.at/ionen-angewandte-physik/index.html.en - Institute for Ion Physics and Applied Physics, University of Innsbruck

Dr. Christian Flatz | Universität Innsbruck

Further reports about: Applied Physics Ion chemical reaction fluorine iodine methyl

More articles from Physics and Astronomy:

nachricht Cherned up to the maximum
10.07.2020 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Porous graphene ribbons doped with nitrogen for electronics and quantum computing
09.07.2020 | University of Basel

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

X-ray scattering shines light on protein folding

10.07.2020 | Life Sciences

Looking at linkers helps to join the dots

10.07.2020 | Materials Sciences

Surprisingly many peculiar long introns found in brain genes

10.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>