Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Animated Movie of Ice

07.01.2008
Melting ice crystals in a computer animation

An animated movie shows an ordered structure dissolving little by little into a disordered mess after a light pulse: Swedish researchers from the University of Uppsala have used a computer to simulate ice melting after it is heated with a short light pulse.

As they report in the journal Angewandte Chemie, the absorbed energy first causes the OH bonds to oscillate. After a few picoseconds (10-12 s) the energy is converted into rotational and translational energy, which causes the crystal to melt, though crystalline domains remain visible for quite a while.

The common form of ice crystals is known as hexagonal ice. In this form the oxygen atoms of the water molecules are arranged in a tetrahedral lattice. Each water molecule is bound to four neighboring molecules by means of bridging hydrogen bonds, leading to an average of two bridges per molecule. In water, there are, on average, only 1.75 bridging hydrogen bonds per molecule.

... more about:
»Melting »PuLSE »crystalline »picosecond

What happens in the process of melting? Carl Caleman and David van der Spoel have now successfully used a computer to simulate “snapshots” of melting ice crystals. These molecular dynamics simulations are ideal for gaining a better understanding of processes like melting or freezing because they make it possible to simultaneously describe both the structure and the dynamics of a system with atomic resolution and with a time resolution in the femtosecond (10-15 s) range.

The simulation demonstrated that the energy of the laser pulse initially causes the OH bonds in the water molecules to vibrate. Immediately after the pulse, the vibrational energy reaches a maximum. After about a picosecond, most of the vibrational energy has been transformed into rotational energy. The molecules begin to spin out of their positions within the crystal, breaking the bridging hydrogen bonds. After about 3 to 6 picoseconds, the rotations diminish in favor of translational motion.

The molecules are now able to move freely and the crystal structure collapses. This process starts out locally, at individual locations within the crystal. Once the symmetry of the structure is broken, the likelihood of melting processes occurring in the area immediately surrounding the crystal defect rises significantly. The melting process thus spreads out from this point little by little. At other locations the ice can maintain its crystalline structure a little longer.

A movie is available online at http://xray.bmc.uu.se/molbiophys/images/Movies/melt.mpg

Author: David van der Spoel, Uppsala University (Sweden), mailto:spoel@xray.bmc.uu.se

Title: Picosecond Melting of Ice by an Infrared Laser Pulse: A Simulation Study

Angewandte Chemie International Edition, doi: 10.1002/anie.200703987

David van der Spoel | Angewandte Chemie
Further information:
http://pressroom.angewandte.org
http://xray.bmc.uu.se/molbiophys/images/Movies/melt.mpg

Further reports about: Melting PuLSE crystalline picosecond

More articles from Life Sciences:

nachricht Solving the efficiency of Gram-negative bacteria
22.03.2019 | Harvard University

nachricht Bacteria bide their time when antibiotics attack
22.03.2019 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>