Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hot Water in Cold Comets

13.09.2010
Comets, also named “dirty snowballs”, are largely composed of water. An international research team around Andreas Wolf, of the Max-Planck Institute for Nuclear Physics in Heidelberg, Germany, recently succeeded deciphering an important aspect of the way by which water molecules often form in space. As a surprise, the water molecules produced under cold, dilute conditions turned out to be produced as particles as hot as 60,000 Kelvin. In their research the physicists, though, did not use a telescope, but a particle accelerator (Physical Review Letters, 3 September 2010)

In comets as well as in interstellar clouds, the precursor molecule of water is the positively charged hydronium ion H3O+. This molecular ion can be detected from earth by telescopes. In the cosmic clouds negatively charged electrons are also present, causing frequent collisions.

In those the hydronium ion converts to the neutral instable radical H3O, which rapidly decays. “For this break-up reaction, nature offers three choices”, describes Andreas Wolf: forming either H2O plus H, or OH plus H2, or OH plus two H atoms. Present research tries to determine the yields of these production channels, including that of water.

Wolf and his colleagues investigated this question by reproducing the electron attachment in the laboratory. They used the Heidelberg Test Storage Ring, a racetrack of sorts, with a 55-meter circumference, on which charged particles race around, guided by magnets.

It is into this ring that the scientists direct the hydronium ions which, more precisely, carry heavy hydrogen atoms in order to render them more suitable for the experiments performed. At one position of the ring, electrons are admitted in addition, which then proceed together with the ions over a straight length of almost two meters and then leave the racetrack again. This happens on each turn, that is several hundred thousand times per second.

In the electron bath, similar to the process in space, electrons attach to the hydronium ions, thus forming rapidly decaying neutral molecules. The fragments from this process do not carry any net electric charge. Hence, they do not feel the magnetic field keeping the ions on their circular orbits and rather continue their straight motion. At the place where they leave the racetrack, Wolf's research team has positioned a detector that records the impacting fragments. This single-particle counter has been created in collaboration with colleagues from the Weizmann Institute of Science in Rehovot, Israel.

In up to one thousand snapshots per second, the detector records the masses and the momenta of all fragments from individual molecular breakup reactions. With these data, the molecular dynamics triggered by the electron attachment and leading to the fragmentation can be reconstructed exactly.

The first important result: 16.5 per cent of all decays following the electron attachment lead to the water molecule. “This is quite a high number”, says Wolf. “Electron attachment to hydronium ions can well be the most important pathway for water production in interstellar clouds and comets.”

Most frequently, with a yield of 71 per cent, the hydronium ions in this experiment are found to break up into three fragments, namely OH and two hydrogen atoms (in their heavy-hydrogen equivalents). The researchers can now understand the reason for this behavior. Its origin is the large binding energy released by the attachment of the electron. The entire molecule feels this binding energy and starts a vibration similar to a spring one stretches and then releases. “To general surprise we found that the water molecules vibrate with about the maximum energy which they can possibly support”, says Wolf. With this, each water molecule resulting from the electron capture is close to rupture: the cause for the three-body fragmentation to become that frequent.

The high vibrational energy observed can be converted into a temperature. It results in about 60,000 Kelvin: water is created truly hot.

The new evidence has further consequences. On the one hand, it provides input for computer models which reproduce the complex chemical reaction network in interstellar clouds. On the other hand, it explains mysterious signatures found by astronomers in the infrared spectra of some comets. These signatures indicate the infrared radiation emitted by hot water molecules during stepwise “de-excitation” of strong vibrational motion. Not of the least interest are, finally, the detailed conclusions that can be drawn from the molecular breakup experiments about the electronic processes in a hydronium ion, which serve as input for quantum mechanical models of these molecules.

Original paper:

H. Buhr, J. Stützel, M. B. Mendes, O. Novotný, D. Schwalm, M. H. Berg, D. Bing, M. Grieser, O. Heber, C. Krantz, S. Menk, S. Novotny, D. A. Orlov, A. Petrignani, M. L. Rappaport, R. Repnow, D. Zajfman, and A. Wolf
Hot water molecules from dissociative recombination of D3O+ with cold electrons
Physical Review Letters 105, 103202 (2010)
Contact:
Prof. Dr. Andreas Wolf
Max-Planck-Institut für Kernphysik, Heidelberg
Phone: +49 6221 516-503
e-mail: A.Wolf@mpi-hd.mpg.de
Dr. Henrik Buhr
Max-Planck-Institut für Kernphysik, Heidelberg
Phone: +49 531 5926-208
e-mail: henrik.buhr@mpi-hd.mpg.de

Dr. Bernold Feuerstein | idw
Further information:
http://link.aps.org/doi/10.1103/PhysRevLett.105.103202
http://www.mpi-hd.mpg.de/blaum/members/molecular-qd/index.en.html

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>