Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Help from the Dark Side

09.08.2010
Using "dark channel" fluorescence, scientists can explain how biochemical substances carry out their function

Spectroscopic techniques are among the most important methods by which scientists can look inside materials. Now, using X-ray absorption spectroscopy, researchers from Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) have observed the moving of electric charges from solute to solvent – the electron transfer. They can find out how solute biochemical substances carry out their microscopic functions in their natural environment at room temperature and normal pressure. Until recently, studying such systems by soft X-ray radiation has not been possible.

The HZB group led by Emad Aziz reports on this in Nature Chemistry in the online pre-issue from 8 August.

The group studied the X-ray absorption spectra of iron ions in both iron chloride and organic compounds such as haemin, the active centre of blood component haemoglobin, and analyzed the hitherto inexplicable negative peak (dip) in the spectra.

In X-ray absorption spectroscopy, monochromatic X-ray light interacts with the sample. When the energy of the incident light exactly matches the energy transfer in the molecule, electrons can be excited out of their ground state into a higher energy state. As they return to their original state, the added energy is released again, as an emission of fluorescent light for example. By recording this fluorescent light, scientists gain an insight into the electron orbital configuration of atoms and molecules.

By making measurements using synchrotron light at the X-ray source BESSY II, Emad Aziz and his colleagues discovered that certain solute substances emit no fluorescent light after excitation. The negative peak that appeared in the spectrum was evidence that the return to ground state took place without radiation, through a so-called “dark channel”.

This happens because interactions between molecules in the sample and in the solvent produce common orbitals. The excited electrons are pushed into these orbitals. “This works because the molecular orbitals of the iron and water ions come very close spatially and their energies match very well,” explains Emad Aziz, head of a junior research group at HZB. The electrons remain in this new state longer than they would in a normal molecular orbital. Their energy state therefore prevents the emission of the normally expected fluorescent light.

Dips in the spectrum thus give a clue as to the kind of interplay between the sample and the solvent. One could use this process to examine how much the solvent contributes towards the function of biochemical systems such as proteins, for example.

Ultrafast processes such as charge transfer have only been observable with enormous effort using conventional methods. Now, HZB researchers have found a way to explain the dynamics of this process using a simple model. “We can observe where the charges migrate to, and we can see that this happens within a few femtoseconds,” Emad Aziz stresses. The result also has major repercussions for the interpretation of X-ray absorption spectra in general.

For their experiments, the group used a specially developed flow cell that also allows them to study biological samples by X-ray in their natural environment – that is in dissolved form.

Nature Chemistry Article: DOI: 10.1038/NCHEM.768

Kathrin Lange
Tel.: +49 30 8062-14621
kathrin.lange@helmholtz-berlin.de
Dr. Emad Flear Aziz Bekhitit
Tel.: +49 30 8062-15003
emad.aziz@helmholtz-berlin.de
Press Office:
Dr. Ina Helms
Tel +49 30 8062-42034, -14922
Fax +49 30 8062-42998
ina.helms@helmholtz-berlin.de

Dr. Ina Helms | Helmholtz-Zentrum
Further information:
http://www.helmholtz-berlin.de

More articles from Materials Sciences:

nachricht Serendipity uncovers borophene's potential
23.02.2017 | Northwestern University

nachricht Switched-on DNA
20.02.2017 | Arizona State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>