Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Filming chemistry with a high speed x-ray camera

05.12.2014

Chemistry happens all around us. A chemical reaction is a rearrangement of atoms in and between molecules, the breaking of old and the formation of new bonds. The glue that binds atoms in molecules and creates the bonds between them is made out of valence electrons.

Scientists of the Max-Born-Institut (MBI) in Berlin were able to show theoretically that the ultrafast x-ray camera is not only sensitive to inert core electrons but may also visualize the motion of chemically active valence electrons.


Filming bond making and bond breaking during a pericyclic reaction.

(credit: MBI)


The breaking and making of chemical bonds along different reaction paths.

(credit: MBI)

While the motion of valence electrons is at the very heart of chemical reactions, only a small fraction among them participates actively. The valence electron charge transferred between the atoms is often just a fraction of the charge of an electron.

And those that do participate, do it very quickly: the duration of many very important chemical processes, such as first steps in vision and light harvesting, is measured in only tens to a hundred of femtoseconds - a femtosecond is a millionth of a billionth of a second. Making a movie of the chemically active electrons is therefore very challenging.

First, one needs a camera with exquisite temporal and spatial resolution. Second, one needs a very sensitive camera. Indeed, one would really like to see not just how the atoms move, but also how the new bonds are formed as the old ones are broken - and this means filming the few active valence electrons in the sea of all electrons attached to the many atoms in the molecule.

An X-ray camera easily fits the first requirement. X-ray scattering has been indispensable in studying the structure of matter with atomic-scale spatial resolution since the discovery of x-rays. Thanks to enormous technological progress, it is now becoming possible to generate ultrashort flashes of x-rays, adding femtosecond temporal resolution to structural sensitivity. These flashes of x-rays promise to provide stroboscopic snapshots of chemical and biological processes in individual molecules.

However, fitting the second requirement - the sensitivity to active valence electrons - has never been the strength of an x-ray camera. X-ray scattering is always dominated by core and inert valence electrons. The small fraction of valence electrons actively participating in a chemical reaction is generally presumed lost in the scattering signal, seemingly placing ultrafast x-ray imaging of these electron densities out of the realm of possibility

Our work, published in Nature Communications, suggests a way to resolve this challenge. In this work, we theoretically demonstrate a robust and effective method to extract the contributions of chemically active valence electrons from the total x-ray scattering by a single molecule - a critical step in the endeavor to film bond making and bond breaking as it happens, in space and time. Our paper shows how, by combining the standard analysis of the full x-ray scattering pattern with an additional analysis of the part of the scattering pattern, which is limited to relatively small momentum transfer, one nearly effortlessly brings to the fore the motion of chemically active valence electrons.

The work not only showed how to film chemically active valence electrons with x-rays, it has also provided an experimental access to the long-standing problem: Are the new bonds made at the same time as old bonds are broken, or is there a time-delay between these two processes?

The x-ray camera confirms that the answer depends on whether the atoms have enough energy to climb over the energy barrier, which separates reactants from products, or if they have to resort to the quantum trick of tunneling through the energy barrier the only option available when their energy is not sufficient to overcome it. In the first case we confirm a time-delay between the breaking of old and the formation of new bonds. In the second case, we see no delay: the new bonds are built in concert with the destruction of the old ones. We hope our work will bring new insights into ways to initiate and control complex chemical and biological reactions.

Original publication:
Timm Bredtmann, Misha Ivanov, Gopal Dixit
X-ray imaging of chemically active valence electrons during a pericyclic reaction
Nature Communication doi:10.1038/ncomms6589

Fig. 1: Filming bond making and bond breaking during a pericyclic reaction: We show theoretically that the ultrafast x-ray camera is not only sensitive to inert core electrons but may also visualize the motion of chemically active valence electrons. (credit: MBI)

Abb.: A combination of the standard analysis of the full x-ray scattering pattern (A, B) with an additional analysis of the part of the scattering pattern, which is limited to relatively small momentum transfer, one nearly effortlessly brings to the fore the motion of chemically active valence electrons during a pericyclic reaction (C, D). The breaking and making of chemical bonds along different reaction paths may thus be filmed and analyzed directly. (credit: MBI)

Contact
Dr. Timm Bredtmann Tel: 030 6392 1239
Prof. Misha Ivanov Tel: 030 6392 1210
Dr. Gopal Dixit Tel: 030 6392 1239

Max-Born-Institut (MBI)
im Forschungsverbund Berlin e.V
Max-Born-Straße 2A
12489 Berlin
GERMANY

Tel. ++49 30 6392 1505
Fax. ++49 30 6392 1509
Email: mbi@mbi-berlin.de


Weitere Informationen:

http://www.mbi-berlin.de

Karl-Heinz Karisch | Forschungsverbund Berlin e.V.

More articles from Life Sciences:

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

nachricht Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Global threat to primates concerns us all

19.01.2017 | Ecology, The Environment and Conservation

Scientist from Kiel University coordinates Million Euros Project in Inflammation Research

19.01.2017 | Awards Funding

The Great Unknown: Risk-Taking Behavior in Adolescents

19.01.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>