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 Novel sensors could enable smarter textiles
17.08.2018 | University of Delaware

nachricht Quantum material is promising 'ion conductor' for research, new technologies
17.08.2018 | Purdue 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: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Quantum bugs, meet your new swatter

20.08.2018 | Information Technology

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>