Dance of the atoms: Clustering of atoms observed
June 10, 2013 — Lone people standing in a ballroom don't tend to move a lot. It's only when they find a suitable dance partner that rapid motion sets in. Atoms on iron-oxide surfaces behave in a similar way: Only with the right molecular partner do they dance across the surface. Scientists at the Vienna University of Technology have now filmed the atoms, proving that carbon monoxide is the partner responsible for the quick motion. Their movies show that the motion leads directly to clustering -- an effect that can do great harm in catalysts.
The findings have now been published in the journal Nature Materials.
Clusters -- What a Waste of Atoms!
"Metals such as gold or palladium are often used as catalysts to speed up certain chemical reactions," says Professor Ulrike Diebold (Institute of Applied Physics, Vienna University of Technology). When the atoms ball together, most of them do not get into contact with the surrounding gas any more and the catalytic effect diminishes drastically. For this reason, Ulrike Diebold's team investigates how clusters form from single atoms on a surface, and search for ways to inhibit the process.
Theories about this effect have been discussed for years, but the researchers at the Vienna University of Technology have now directly observed the clustering of the atoms. "We are using palladium atoms on an extremely clean iron-oxide surfaces in an ultra high vacuum chamber. For several hours, we take pictures of the surface with a scanning tunneling microscope," says Gareth Parkinson (Vienna University of Technology). These pictures were then made into a movie, in which the paths of the individual atoms could be tracked.
The Skyhook Effect
Using this technique, the research team discovered that the rapid atomic dance on the surface is initiated by carbon monoxide molecules, which bind to individual palladium atoms. As soon as this happens, the palladium is hardly connected to the ground and can move around almost freely, as if it had been lifted out by the carbon monoxide. "This is known as the skyhook effect," says Zbynek Novotny (Vienna University of Technology).The carbon monoxide and palladium move happily together across the surface, until they collide with other 'dancing couples'. Then, they stick together creating a small cluster that continues to grow.
Hydroxyl Against Clustering?
With the new possibility of watching clustering in real-time under the microscope, the mechanisms can now be studied in detail: "We discovered that OH groups on the surface can suppress the clustering effect," says Gareth Parkinson. If the carbon monoxide-palladium couples do not encounter each other, but instead find an OH group, they get trapped there and cannot form a cluster. A hydroxyl coating of the surface could therefore lead to a significant improvement of the stability of catalysts.
Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com
Electronic Components distributor:http://www.suvsystem.com
Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html
IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html
LED Distributor:http://www.suvsystem.com/l/LED-1.html
Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html
Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html
Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html
Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html
SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc
we are focus on the following fields,and hope we can help you.
CMF5564K200BER670 CMF5564R900FKRE CMF5564R900FKR870 CMF5564R900FKR8 CMF5564R900FKR770 CMF5564R900FKR7 CMF5564R900FKR670 CMF5564R900FKR6 CMF5564R900FKEK CMF5564R900FKEB70 CMF5564R900FKEB CMF5564R900FKEA70 CMF5564R900FKEA CMF5564R900FKBF CMF5564R900FHEB CMF5564R900FHBF CMF5564R900DHWF CMF5564R900DHRE CMF5564R900DHR8 CMF5564R900DHR7 CMF5564R900DHR6 CMF5564R900DHEK CMF5564R900DHEB CMF5564R900DHEA CMF5564R900DHBF CMF5564R900BHRE CMF5564R900BHEA CMF5564R200BHWF CMF5564R200BHR8 CMF5564R200BHR7 CMF5564R200BHR6 CMF5564R200BHEK CMF5564R200BHEB CMF5564R200BHBF CMF5564R000FKEK CMF5564R000BEWF CMF5564R000BER8 CMF5564R000BER7 CMF5564R000BER6 CMF5564R000BEEK
http://www.suvsystem.com/a/2472.aspx
