Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Experiments help explain mysterious ’floppy’ space molecule

06.01.2006


A laboratory method developed for making and analyzing cold, concentrated samples of a mysterious "floppy" molecule thought to be abundant only in outer space has revealed new data that help explain the molecule’s properties.



The advance, described in the Jan. 6 issue of Science,* is a step toward overcoming a decades-old challenge in chemistry--explaining reactions that occur within very cold clouds among the stars, and perhaps for developing new chemical processes. The paper combines experiments performed by David Nesbitt and colleagues at JILA, a joint institute of the Commerce Department’s National Institute of Standards and Technology (NIST) and University of Colorado at Boulder, with theoretical predictions made with Joel Bowman at Emory University in Atlanta, Ga., and Anne McCoy at The Ohio State University in Columbus, Ohio.

Most molecules have a rigid three-dimensional (3D) structure. The subject of the new study is "protonated" methane, which contains one carbon atom and five hydrogen atoms, one of which is ionized, leaving nothing but a proton (a particle with a positive charge). The five protons from the hydrogen atoms scramble for four bonds around the molecule as if playing a continuous game of musical chairs. In the process, the molecule classically vibrates and rotates in a bizarre manner, morphing between several 3D structures with nearly identical energy levels. (Animation available at http://www.nist.gov/public_affairs/images/floppy_animation.htm.) Chemists have spent decades trying to explain why and how this occurs, a challenge that has seemed insurmountable until recently.


Protonated methane is a so-called "super acid." This class of molecule has been shown to be more than a million times more powerful than conventional acids and is more effective in inducing reactions that produce solvents and many other important industrial products.

Many theories have been published on the puzzling behavior of this charged molecule (or ion), but experiments must be done to match the ion’s energy characteristics with its physical motions, and such data are difficult to collect and understand. In particular, scientists are interested in how the molecule absorbs different wavelengths of infrared (IR) light, which provides clues about nuclear motion and chemical bonds and structures.

The JILA method generates concentrated amounts of the ion at cold enough temperatures to simplify the complex IR spectrum so it can be analyzed. The data strike a balance between detail and simplicity, providing useful information that is still challenging but easier to understand than ever before. This enabled the authors of the Science paper to match predicted changes in energy to specific vibrations and partially characterize the ion’s structure and dynamics. For example, they were able to correlate one intense spectral feature to a transition between two 3D structures with equivalent energy levels.

Previously published spectra of this molecule have either been too low resolution to "see" this motion, or too hot (and therefore too complex) to analyze.

"The experiments have provided the first jet-cooled, high-resolution spectrum of this highly fluxional molecule," says Nesbitt, a NIST Fellow who led the JILA experimental team. "This has been among the most sought-after IR spectra since the first appearance of this molecule in mass spectrometers over 50 years ago. This is a problem that has occupied many careers; every piece helps."

The JILA method involves making methane gas at high temperature and pressure, and expanding it into a vacuum to cool the molecules to 10 K (-442 degrees F). The cold molecules then file through an opening just 1 millimeter wide, where they are hit with a "lightning bolt" of electrical current that generates high concentrations of highly reactive ions. The key to mass production is to surround the molecules with enough electrons to make the entire gas mixture neutral in charge, Nesbitt says.

For the analysis step, JILA scientists shine an infrared laser on the cold ions, and detect the light that passes through. The light that is lost, or the small amount absorbed by the molecules, is analyzed to obtain a pattern of absorption at different wavelengths. The technique is very sensitive, thanks to methods for detecting trace absorption of the laser light and manipulating the electrical discharge to maximize the ion concentration levels.

Future and ongoing studies will focus on matching the ion’s IR absorption characteristics with its rotational structure, including end-over-end tumbling. "Protonated methane still has a few tricks up its sleeve," Nesbitt cautions.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov/public_affairs/images/floppy_animation.htm

More articles from Life Sciences:

nachricht Hunting pathogens at full force
22.03.2017 | Helmholtz-Zentrum für Infektionsforschung

nachricht A 155 carat diamond with 92 mm diameter
22.03.2017 | Universität Augsburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>