Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Silver-rich Lumps

09.01.2008
Large cluster complexes with almost 500 silver atoms

Nanoscopic “lumps” of atoms, known as clusters, are the specialty of a research team headed by Dieter Fenske from the University of Karlsruhe and the Forschungszentrum Karlsruhe. The production and characterization of clusters made of interesting semiconductor materials are a main focus of this group.

As reported in the journal Angewandte Chemie, the team has now been able to synthesize four new, particularly large and silver-rich clusters, and to determine their crystal structures.

Two or three-dimensional nanostructures of semiconductor materials are of interest for future nanoelectronic applications. Such structures could be built of arrays of clusters. A cluster is an accumulation of atoms or molecules that includes hundreds or thousands of atoms. Tiny as they are, to some degree clusters have completely properties to those of “normal sized” (macroscopic) solid particles. This difference is caused by the high surface-to-volume ratio. In order to precisely interpret the measured physical properties of clusters, it is important to understand the atomic structure of these nanoparticles.

... more about:
»Atoms »structure

One of the things Fenske and his team are working on is the synthesis of metal-rich clusters of the elements sulfur, selenium, and tellurium (the chalcogens). For the metallic component in these systems, the coinage metals copper and silver are well suited. By using specially developed synthetic methods, the scientists were able to make molecular cluster complexes. In this process, cluster cores made of metal and chalcogen atoms are surrounded by a protective shell of organic ligands. This protective coat prevents the tiny lumps from aggregating into larger particles or solids. This trick made it possible for the researchers to make particularly large silver-rich clusters. The newest members of this family of clusters consist of distorted spherical silver-chalcogenide cores with diameters between two and four nanometers. Their surfaces are protected with thiolate or phosphane ligands.

Characterizing the structures of such large metal-rich cluster complexes by X-ray crystallographic studies is extremely difficult. It is actually impossible to determine the exact composition. Defects in the crystal lattice are one reason. The tendency to have defects increases as the number of silver atoms grows. However, by using a combination of X-ray diffraction, mass spectrometry, and electron microscopy, the researchers did succeed in deriving idealized empirical formulas and idealized atomic structures for their clusters. The most silver-rich compound consists of clusters with approximately 490 silver and 188 sulfur atoms, as well as 114 sulfur-organic ligands, and an idealized composition [Ag 490S188(StC5H11)114].

Author: Dieter Fenske, Universität Karlsruhe (Germany), http://www.aoc.uni-karlsruhe.de/english/380.php

Title: Synthesis and Crystal Structures of the Ligand-Stabilized Silver Chalcogenide Clusters [Ag154Se77(dppxy)18], [Ag320(StBu)60S130(dppp)12], [Ag352S128(StC5H11)96] and [Ag490S188(StC5H11)114]

Angewandte Chemie International Edition, doi: 10.1002/anie.200704249

Dieter Fenske | Angewandte Chemie
Further information:
http://www.aoc.uni-karlsruhe.de/english/380.php

Further reports about: Atoms structure

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

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...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>