Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Floating Films on Liquid Mercury

17.01.2005


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:
http://www.bnl.gov

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>