Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Measuring Electron Orbitals

16.11.2009
For the first time, it has been possible to measure electron density in individual molecular states using what is known as the photoelectric effect.

Now published in SCIENCE, this method represents a key building block in the development of organic semiconductor elements. Supported by the Austrian Science Fund FWF, the success of this project rested on the mathematical transformation of the measured data.

This made it possible to interpret the distribution of the electrons and draw conclusions about the potential properties of organic semiconductor elements.

Ultra-thin films made of organic molecules form the basis of future semiconductor technologies. Because organic molecules are extremely flexible, they can be used in a whole new range of applications, making it equally possible to create pliable screens and cost-effective solar cells. However, apart from these everyday applications for organic semiconductors, the most important task is to gain a better understanding of the interactions between organic materials and inorganic carrier substances. A team from the Universities of Graz and Leoben has now succeeded in developing a means of doing just that.

TIGHTLY PACKED
"The properties of an organic molecule are defined to a large extent by specific electron states", explains Dr. Peter Puschnig of the Chair of Atomistic Modelling and Design of Materials at the University of Leoben, who led the research. He adds: "If we can determine their distribution within the molecule accurately, then we will be able to better understand how organic semiconductor components work and thus increase their efficiency." Until now, there has been a lack of effective methods of measuring this electron distribution. Dr. Puschnig and his team have therefore succeeded in making significant progress.

The team's achievement is based on the use of the photoelectric effect. This enables individual electrons to be "knocked out" of organic molecules. As part of this project, an organic molecule was exposed to ultraviolet light that emitted sufficient energy to separate individual electrons from the molecules. The direction and speed of the electrons thus released were then measured using highly-sensitive detectors, generating the basic data required to calculate the electron distribution within the molecule. As part of this process, Prof. Michael Ramsay and his team from the University of Graz used a hexaphenyl film just one molecule thick that had been applied to a copper surface. The team from Graz carried out the actual measurements at the Berliner Elektronen-Speicherring Gesellschaft für Synchrotronstrahlung (BESSY, Berlin Electron Storage Ring Society for Synchrotron Radiation).

A CALCULATED RESULT
Commenting on the evaluation of this data, Dr. Puschnig says: "It revealed a quite characteristic distribution of the electrons emitted. However, it initially proved difficult to interpret this distribution and it seemed it would be impossible to link the measured data to the original electron distribution in the molecule." It was only by using special mathematical transformations (Fourier Transformation) that the team was able to establish that the measured electron distribution matched that of the molecule. As the distribution was in this instance already known from calculations carried out as part of the density functional theory, it was possible to test and confirm the viability of the new method.

This new method is particularly valuable as it means measuring the behaviour of electrons at the interfaces between organic semiconductors and metals is now relatively easy and highly accurate. The study "Interface controlled and functionalised organic thin films" supported by the FWF as part of the National Research Network (NFN) is thus making a fundamental contribution to future applications of organic semiconductors.

Original publication: Reconstruction of Molecular Orbital Densities from Photoemission Data, P. Puschnig, S. Berkebile, A. J. Fleming, G. Koller, K. Emtsev, T. Seyller, J. D. Riley, C. Ambrosch­Draxl, F. P. Netzer, M. G. Ramsey: Science 326, 702 (2009).

Scientific Contact:
Dr. Peter Puschnig
University of Leoben
Chair for Atomistic Modelling and Design of Materials T +43 / 3842 / 402 4403 E peter.puschnig@unileoben.ac.at
Austrian Science Fund FWF:
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Vienna
Austria
T +43 / 1 / 505 67 40 - 8111
E stefan.bernhardt@fwf.ac.at
Copy Editing & Distribution:
PR&D - Public Relations for Research & Education Campus Vienna Biocenter 2 1030 Vienna Austria T +43 / 1 / 505 70 44 E contact@prd.at W http://www.prd.at

Stefan Bernhardt | PR&D
Further information:
http://www.fwf.ac.at
http://www.fwf.ac.at/en/public_relations/press/pv200911-en.html

More articles from Materials Sciences:

nachricht Flying: Efficiency thanks to Lightweight Air Nozzles
23.10.2017 | Technische Universität Chemnitz

nachricht Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>