Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Movement of pyrrole molecules defy 'classical' physics

Abstract:
New research shows that movement of the ring-like molecule pyrrole over a metal surface runs counter to the centuries-old laws of 'classical' physics that govern our everyday world.

Movement of pyrrole molecules defy 'classical' physics

Cambridge, UK | Posted on April 28th, 2013

Using uniquely sensitive experimental techniques, scientists have found that laws of quantum physics - believed primarily to influence at only sub-atomic levels - can actually impact on a molecular level.

Researchers at Cambridge's Chemistry Department and Cavendish Laboratory say they have evidence that, in the case of pyrrole, quantum laws affecting the internal motions of the molecule change the "very nature of the energy landscape" - making this 'quantum motion' essential to understanding the distribution of the whole molecule.

The study, a collaboration between scientists from Cambridge and Rutgers universities, appeared in the German chemistry journal Angewandte Chemie earlier this month.

A pyrrole molecule's centre consists of a "flat pentagram" of five atoms, four carbon and one nitrogen. Each of these atoms has an additional hydrogen atom attached, sticking out like spokes.

Following experiments performed by Barbara Lechner at the Cavendish Laboratory to determine the energy required for movement of pyrrole across a copper surface, the team discovered a discrepancy that led them down a 'quantum' road to an unusual discovery.

In previous work on simpler molecules, the scientists were able to accurately calculate the 'activation barrier' - the energy required to loosen a molecule's bond to a surface, allowing movement - using 'density functional theory', a method that treats the electrons which bind the atoms according to quantum mechanics but, crucially, deals with atomic nuclei using a 'classical' physics approach.

Surprisingly, with pyrrole the predicted 'activation barriers' were way out, with calculations "less than a third of the measured value". After much head scratching, puzzled scientists turned to a purely quantum phenomenon called 'zero-point energy'.

In classical physics, an object losing energy can continue to do so until it can be thought of as sitting perfectly still. In the quantum world, this is never the case: everything always retains some form of residual - even undetectable - energy, known as 'zero-point energy'.

While 'zero-point energy' is well known to be associated with motion of the atoms contained in molecules, it was previously believed that such tiny amounts of energy simply don't affect the molecule as a whole to any measurable extent, unless the molecule broke apart.

But now, the researchers have discovered that the "quantum nature" of the molecule's internal motion actually does affect the molecule as a whole as it moves across the surface, defying the 'classical' laws that it's simply too big to feel quantum effects.

'Zero-point energy' moving within a pyrrole molecule is unexpectedly sensitive to the exact site occupied by the molecule on the surface. In moving from one site to another, the 'activation energy' must include a sizeable contribution due to the change in the quantum 'zero-point energy'.

Scientists believe the effect is particularly noticeable in the case of pyrrole because the 'activation energy' needed for diffusion is particularly small, but that many other similar molecules ought to show the same kind of behavior.

"Understanding the nature of molecular diffusion on metal surfaces is of great current interest, due to efforts to manufacture two-dimensional networks of ring-like molecules for use in optical, electronic or spintronic devices," said Dr Stephen Jenkins, who heads up the Surface Science Group in Cambridge's Department of Chemistry.

"The balance between the activation energy and the energy barrier that sticks the molecules to the surface is critical in determining which networks are able to form under different conditions."

Credits:

Stephen Jenkins is head of the Chemistry Department's Surface Science Group; Marco Sacchi is the post-doc in that group who did the calculations.

Bill Allison and John Ellis lead the Surface Science section of the Surfaces, Microstructure and Fracture Group at the Cavendish; Holly Hedgeland was a post-doc in that group, who started a lot of the experimental work on diffusion of aromatic molecules; Barbara Lechner was the student who took the lead on the experimental work for this specific system.

Jane Hinch is a collaborator from Rutgers University, involved in the experimental work and its interpretation

####

For more information, please click here

Contacts:
Stephen Jenkins

44-012-233-36502

Copyright © University of Cambridge

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Arrowhead to Present at BioCentury's NewsMakers in the Biotech Industry Conference September 19th, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

New research points to graphene as a flexible, low-cost touchscreen solution September 19th, 2014

Physics

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Excitonic Dark States Shed Light on TMDC Atomic Layers: Berkeley Lab Discovery Holds Promise for Nanoelectronic and Photonic Applications September 11th, 2014

Spintronics

IEEE International Electron Devices Meeting To Celebrate 60th Anniversary as The Leading Technical Conference for Advanced Semiconductor Devices September 18th, 2014

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Molecular engineers record an electron's quantum behavior August 14th, 2014

Diamond defect interior design: Planting imperfections called 'NV centers' at specific spots within a diamond lattice could advance quantum computing and atomic-scale measurement August 5th, 2014

Discoveries

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

New research points to graphene as a flexible, low-cost touchscreen solution September 19th, 2014

Announcements

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Arrowhead to Present at BioCentury's NewsMakers in the Biotech Industry Conference September 19th, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

Photonics/Optics/Lasers

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

The Pocket Project will develop a low-cost and accurate point-of-care test to diagnose Tuberculosis: ICN2 holds a follow-up meeting of the Project on September 18th - 19th September 18th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Quantum nanoscience

Big Results Require Big Ambitions: Three young UCSB faculty receive CAREER awards from the National Science Foundation September 18th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Layered graphene sandwich for next generation electronics September 8th, 2014

Cool Calculations for Cold Atoms: New theory of universal three-body encounters September 2nd, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE