Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular Film on Liquid Mercury Reveals New Properties

15.11.2002


A team of scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Harvard University, and Bar-Ilan University in Israel have grown ultrathin films made of organic molecules on the surface of liquid mercury. The results, reported in the November 15, 2002, issue of Science, reveal a series of new molecular structures that could lead to novel applications in nanotechnology, which involves manipulating materials at the atomic scale.


This schematic drawing shows how the stearic molecules of the film rearrange as they are added onto the surface of the liquid mercury support



Growing molecular films on liquid surfaces is part of an ongoing activity by Brookhaven scientists to create nanomaterials, which are a few billionths of a meter in thickness. Ultrathin films are becoming increasingly important for fast-developing applications, such as faster and smaller electronic and magnetic devices, advanced biotechnological membranes, and controlled drug release in the human body. The Brookhaven team is a leader in the field of liquid surface-supported film growth, with expertise gained over the past 20 years.

"When you grow a film on a solid surface, the molecules of the film tend to interlock with those of the underlying support," says Benjamin Ocko, the Brookhaven physicist who participated in the study. "But an underlying liquid surface is not ordered and provides an ideal setting for studying ultrathin states of matter without the complications of the solid support."


Ocko and his colleagues first filled a small tray with liquid mercury and then deposited on the surface a nanometer-thin film of stearic acid, an organic waxlike material that is a common component of cell membranes. Since stearic acid is not soluble in mercury, it floats on the surface.


To see how the molecules of the film organize on the surface, the scientists measured how x-rays produced by the National Synchrotron Light Source at Brookhaven scattered off the ultrathin molecular film. Key to the study was a unique instrument used for tilting the x-rays downward onto the liquid mercury surface, which was developed by Peter Pershan, a physicist at Harvard and one of the study’s authors, along with the Brookhaven team.

The scientists discovered that, as the number of molecules deposited on the surface increased, they formed four distinct patterns. "First, when a few molecules are deposited, they tend to take as much space as they can, by lying on the surface," explains Henning Kraack, a physics Ph.D. student from Bar-Ilan and the study’s lead author. "When more molecules are added, a second layer of molecules lies on top of the first one.

"Then, as even more molecules are deposited," Kraack continues, "they ’stand up’ to leave more space to neighboring molecules, allowing them to densely pack in one layer. But even then, before standing up straight, the molecules are first tilted to the side, and stand up completely only when they are ’squeezed’ by other molecules that ’elbow their way through.’"

These observations came as a surprise, since previous studies have shown that, when stearic molecules are deposited on water -- the only other liquid support studied so far -- they only stand up on the surface. "Patterns in which molecules lie flat on a liquid surface have never been observed before," Kraack says.

Moshe Deutsch, a physicist at Bar-Ilan and one of the authors of the study, notes that because the liquid mercury does not seem to influence too much the way the stearic molecules assemble, "growing films on a liquid surface is like growing them without support at all." It might be possible to choose a film pattern, he adds, simply by selecting the appropriate molecular coverage.


"This work shows that without an underlying lattice, we can control film growth," Deutsch says. "By growing other molecules on a liquid support, we will be able to control the size and properties of other films, and thus tailor them for different applications, in particular their use in nanoelectronics and nanosensor technology."

This work was funded by the U.S. Department of Energy, which supports basic research in a variety of scientific fields, the National Science Foundation, and the U.S.-Israel Binational Science Foundation in Jerusalem, Israel.

Karen McNulty Walsh | EurekAlert!
Further information:
http://nslsweb.nsls.bnl.gov/nsls/
http://www.bnl.gov/bnlweb/pubaf/pr/2002/bnlpr111402.htm

More articles from Materials Sciences:

nachricht ADIR Project: Lasers Recover Valuable Materials
21.07.2017 | Fraunhofer-Institut für Lasertechnik ILT

nachricht High-tech sensing illuminates concrete stress testing
20.07.2017 | University of Leeds

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>