It's raining pentagons

Mar 08, 2009
A computer generated image of a pentamer ice chain (red and white) on a plane surface (brown). Credit: LCN

This week's Nature Materials (09 March 2009) reveals how an international team of scientists led by researchers at the London Centre for Nanotechnology (LCN) at UCL have discovered a novel one dimensional ice chain structure built from pentagons that may prove to be a step toward the development of new materials which can be used to seed clouds and cause rain.

Although the structure of regular ice is well known at the macroscale, its structures are much more mysterious and less well understood at the nanoscale - particularly when ice forms at an interface with matter as is the case in the higher atmosphere on particles of dust. "For the first time, we have shown that ice can build an extended one dimensional chain structure entirely from pentagons and not hexagons" says Dr Michaelides.

"This discovery leads to fundamental new understanding about the nature of hydrogen bonding at interfaces (there is no a priori rule that hexagons should form) and suggests that when people are searching for new ice nucleating agents which can be used to seed clouds and cause rain, they do not necessarily need to focus on materials that have hexagonal surfaces - other types of surfaces may be good too."

Ice structures are usually built out of simple hexagonal arrangements of water molecules and this hexagonal building block motif is easily observed in the structures of snowflakes. However, during their studies Dr Angelos Michaelides and co-workers from the Fritz Haber Institute, Berlin, and the University of Liverpool have discovered a natural nanoscale ice structure formed of pentagons.

"It is important to understand the structure of ice on the nanoscale, and in particular up against solid surfaces because this is how ice crystals form," explains the paper's first author Dr Javier Carrasco. "We need to understand the structure of ice crystals in the upper atmosphere because they play an important role in the formation of clouds and precipitation."

The formation of nanoscale ice crystals (i.e. nucleation) plays a key role in fields as diverse as atmospheric chemistry and biology. Ice nucleation on metal surfaces affords an opportunity to watch this process unfold at the molecular-scale on a well defined, plane interface. A common feature of structural models for such films of ice is that they are built from hexagonal arrangements of molecules.

In order to address the challenge of characterising ice on the nanoscale, the team from the LCN joined up with a team of experimentalists from the University of Liverpool (lead by Professor Andrew Hodgson) to examine ice formation on a very well defined, atomically flat copper surface. The Liverpool group performed scanning tunneling microscopy experiments and the LCN and Berlin teams carried out ab initio calculations to predict what the microscopy results would be. Only through the combination of these two state-of-the-art approaches were they able to definitively show that the ice structures that form are made from pentagons.

Source: University College London

Explore further: Chemical vapor deposition used to grow atomic layer materials on top of each other

add to favorites email to friend print save as pdf

Related Stories

Tiny crystals to boost solar

Apr 02, 2014

A new approach to studying solar panel absorber materials has been developed by researchers in France, Acta Cryst. (2014). B70, 390. The technique could accelerate the development of non-toxic and readil ...

Mother-of-pearl inspires super-strong material

Mar 24, 2014

Whether traditional or derived from high technology, ceramics all have the same flaw: they are fragile. Yet this characteristic may soon be a thing of the past: a team of researchers led by the Laboratoire ...

An experiment recreates the crust of the moon Europa

Mar 14, 2014

Water, salts and gases dissolved in the huge ocean that scientists believe could exist below Europa´s icy crust can rise to the surface generating the enigmatic geological formations associated to red-tinged ...

New material could help with carbon storage

Feb 27, 2014

New research led by University of Nebraska-Lincoln chemist Xiao Cheng Zeng has led to the discovery of a new material that could have significant implications for a variety of challenges, from carbon dioxide ...

Recommended for you

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

(Phys.org) —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

Polymer microparticles could help verify goods

Apr 13, 2014

Some 2 to 5 percent of all international trade involves counterfeit goods, according to a 2013 United Nations report. These illicit products—which include electronics, automotive and aircraft parts, pharmaceuticals, ...

New light on novel additive manufacturing approach

Apr 11, 2014

(Phys.org) —For nearly a century, electrophoretic deposition (EPD) has been used as a method of coating material by depositing particles of various substances onto the surfaces of various manufactured items. ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

LariAnn
not rated yet Mar 09, 2009
Interesting - if water molecules can arrange in pentagons as well as hexagons, then perhaps, under the proper conditions, they can be arranged in a form like unto a geodesic dome, which consists of hexagons and pentagons. What intriguing properties might such a water structure have?

More news stories

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...