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 Space radiation won't stop NASA's human exploration
18.10.2017 | NASA/Johnson Space Center

nachricht Study shows how water could have flowed on 'cold and icy' ancient Mars
18.10.2017 | Brown University

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>