Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hot and cold moves of cyanide and water

07.09.2009
Temperature determines which molecule rocks out

Scientists have long known that molecules dance about as the temperature rises, but now researchers know the exact steps that water takes with a certain molecule. Results with small, electrically charged cyanide ions and water molecules reveal that water zips around ions to a greater extent than expected. The findings improve our understanding of a chemical interaction important in environmental and atmospheric sciences.

"One of the cornerstones of Department of Energy nuclear cleanup missions and climate research is a fundamental understanding of water and ions, one of the most common chemical interactions in the environment," said chemist Xue-Bin Wang of the DOE's Pacific Northwest National Laboratory and Washington State University.

"We've developed a new instrument to probe the dynamics of ions in water," Wang said. "And we've combined theory and modeling to make sense of those experiments, giving us a deeper fundamental understanding of what is happening with this ubiquitous molecule – water."

Wang, PNNL physical chemist Sotiris S. Xantheas, physical chemist Lai-Sheng Wang of PNNL and WSU, and their colleagues published the results in the Journal of Physical Chemistry A. The journal featured their work on the cover of its September 3 issue.

Thirst for Details

Environmental scientists want to know how contaminants move through watery environments below ground, and atmospheric scientists want to know how small particles flutter through water vapor in the sky. To get at the basics, they study a simpler interaction: water and ions, small atoms or molecules that have a slight electrical charge and exist everywhere in nature.

For example, when common table salt -- sodium chloride -- dissolves in water, the negatively charged chloride ions (Cl–) and the positively charged sodium ions (Na+) each interact separately with the water molecules.

Previous work with chloride ions and water has yielded conflicting results about how a water molecule (which is shaped like a boomerang) and a chloride ion (shaped like a ball) face each other. Other groups study barbell-shaped cyanide ions because many molecules found naturally in the environment contain cyanide. The chemical interactions of water and either chloride or cyanide are influenced by the charge and the shape of the molecules, as well as the temperature in which they find themselves.

But directly observing temperature's role in how water and cyanide ions interact has been difficult. So, the team developed a unique instrument that allowed them to precisely control the temperature down to almost absolute zero, or the temperature at which everything freezes. The team used "temperature-controlled photoelectron spectroscopy" in EMSL, the DOE's Environmental Molecular Sciences Laboratory on the PNNL campus, to determine how tightly one cyanide ion and one to three water molecules interact at the very low temperature of -438 F (12 Kelvin) and again at ambient temperature of 80 F (equivalent to 300 Kelvin).

Unexplained Energy

The team measured the molecules' "electron binding energy" at low and high temperatures. This energy is an indication of how tightly the molecules hold onto their electrons -- the tighter the hold, the stronger the bonds that will form between molecules. The team found that ones at low temperature exhibited higher electron binding energy than the ones at high temperatures, as they had expected. However, the difference between the two scenarios was greater than the team expected.

To explore the unexpected difference in energy, the researchers ran computer simulations on the Chinook supercomputer in EMSL. This also let them determine how the boomerang-shaped water and barbell-shaped cyanide faced each other. First they estimated how much energy the molecules used to take different configurations. Then they compared the computer-based estimates to the data they collected in their unique instrument at different temperatures.

The team found that the molecules behaved differently at cold and warm temperatures. At lower temperatures, the boomerang-shaped water held still while the cyanide teetered at the end of one of water's two arms. There, the cyanide flipped, sometimes pointing its carbon (C) atom towards the water's arm, and sometimes pointing its nitrogen (N). At the coldest temperature tested, -438 F, the molecules froze, with cyanide pointing its nitrogen end at the water.

Hot to Trot

At ambient temperatures, however, the barbell-shaped cyanide held steady while the water molecule rocked and flipped around the cyanide. Although the researchers were surprised at how much the water moved, the many positions water could take explained why they saw less electron binding energy than they expected at room temperature: A wiggly water means that the bond between molecules isn't that tight.

"Water can interact with cyanide's carbon or nitrogen and rock back and forth on one atom," said Wang. He added that the detail they get with this instrument is impressive. "Scientists have known for years that atoms move around when temperature rises. Now they can determine the most probable position that the molecule is in at different temperatures."

The results also explain the conflicting results with chloride ions and water, the researchers said, because of the importance of temperature on that interaction as well.

The researchers plan to follow up with studies that include many water molecules and ions at once, as well as with more complex ions than cyanide.

Other authors include PNNL's Karol Kowalski and Alfred Laubereau and Jasper Werhahn from the Technical University of Munich at Garching.

Reference: Xue-Bin Wang, Jasper C. Werhahn, Lai-Sheng Wang, Karol Kowalski, Alfred Laubereau, and Sotiris S. Xantheas, Observation of a Remarkable Temperature Effect in the Hydrogen Bonding Structure and Dynamics of the CN–(H2O) Cluster, J. Phys. Chem. A, DOI 10.1021/jp9034002 (http://pubs.acs.org/doi/abs/10.1021/jp9034002).

This work was supported by the Department of Energy's Office of Basic Energy Sciences within the Office of Science.

EMSL, the Environmental Molecular Sciences Laboratory, is a national scientific user facility sponsored by the Department of Energy's Office of Science, Biological and Environmental Research program that is located at Pacific Northwest National Laboratory. EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. EMSL's technical experts and suite of custom and advanced instruments are unmatched. Its integrated computational and experimental capabilities enable researchers to realize fundamental scientific insights and create new technologies. EMSL's Facebook page.

Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America's most intractable problems in energy, national security and the environment. PNNL employs 4,250 staff, has a $918 million annual budget, and has been managed by Ohio-based Battelle since the lab's inception in 1965. Follow PNNL on Facebook, Linked In and Twitter.

Mary Beckman | EurekAlert!
Further information:
http://www.pnl.gov

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>