Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Floating Films on Liquid Mercury


New results may lead to advances in nanotechnology, molecular electronics

Scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Bar-Ilan University, and Harvard University have grown ultrathin films of organic chain molecules on the surface of liquid mercury and discovered that the molecules form ordered structures. Similar to sixty years ago when fundamental studies of silicon paved the way to the semiconductor-electronics age, these results help to build a foundation for the development of tiny circuits built using organic molecules — called molecular electronics — a field believed to be the future of many electronic applications.

The scientists are participating in an ongoing program at Brookhaven to grow ultrathin organic films on solid and liquid surfaces. They are most interested in films that have controllable properties at a thickness of just a few nanometers, or billionths of a meter, so that they can engineer technologies based on these properties. In addition to being useful for molecular electronics development, ultrathin organic films are becoming increasingly important for many other emerging technologies, such as flexible electronic displays and advanced biotechnological materials that can, for example, mimic the function of cell membranes.

“We decided to use liquid mercury as a surface, instead of a solid,” said Brookhaven physicist Benjamin Ocko, the lead author of the study, reported in the January 12, 2005, online edition of Physical Review Letters. “Liquid surfaces are disordered, hence they do not impose a structure of their own on the film. This makes them important testing grounds for organic thin film growth.”

The researchers filled a small tray with a layer of liquid mercury and deposited a controlled amount of the organic molecules, called alkyl-thiol, onto its surface. “We chose alkyl-thiol because one end of each molecule is terminated by a sulfur atom that bonds strongly to metal surfaces,” explained Henning Kraack, a physicist from Bar-Ilan who participated in the study. “Thiol molecules have been studied extensively on gold surfaces, but the exact nature of the sulfur-gold bond has remained controversial. One of our main goals was to determine the nature of the bond between a similar pair: sulfur and mercury.”

The scientists used x-rays from the National Synchrotron Light Source at Brookhaven, a facility that produces x-ray, infrared, and ultraviolet light for research in many fields. They measured how x-rays scattered off the film from different angles using a unique instrument they developed that tilts the x-rays downward onto the liquid mercury surface. The scientists repeated this procedure several times, adding more alkyl-thiol each time to follow how the structure of the film evolved as the density of molecules increased.

The scientists discovered that three distinct scattering patterns emerged as the alkyl-thiol density was increased on the mercury surface, with each pattern corresponding to a different degree of molecular order. At the lowest density, the molecules lay flat on the mercury’s surface. At an intermediate density, the molecules tilt so that the sulfur end is in contact with the mercury. Finally, at the highest density, the molecules stand up straight.

The x-ray analysis of the lying-down phase showed that the alkyl-thiol molecules are disordered, pointing in all different directions. However, the standing-up and tilted phases are very ordered, with the molecules arranged in crystalline patterns, despite the disordered liquid nature of the underlying mercury. Additionally, the tilted phase contains an unusual structural feature: The alkyl-thiol chain portions and sulfur atoms line up differently so that the chains form one pattern while the sulfur atoms form another.

“The x-ray analysis indicates that the sulfur atoms from two neighboring chains chemically bond to one underyling mercury atom,” explained Ocko. “In the tilted phase, the sulfur-mercury bonds exhibit crystalline order. These bonds also form in the standing-up phase, but, surprisingly, they appear disordered.”

“These specific structural and chemical details are necessary for understanding the electronic properties of the film, which is necessary for determining how to use them in new technologies,” he said.

In upcoming research, Ocko and his colleagues plan to study the structure of molecular layers sandwiched between two conducting surfaces, a configuration directly relevant to molecular electronics. This work was funded by the Office of Basic Energy Sciences within the U.S. Department of Energy’s Office of Science and the U.S.-Israel Binational Science Foundation.

Laura Mgrdichian | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>