Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hydrogen gas: Under pressure

17.01.2011
Simulations have explained the peculiar nature of molecular hydrogen vibration under high pressure

Most of our Universe consists of hydrogen atoms, which are often found under extraordinarily high pressure as high as tens of millions of times the atmospheric pressure of Earth. Understanding the exotic physics of such a high-pressure regime will contribute to our understanding of planet formation, hydrogen storage, room temperature superconductivity and other fields, explains Toshiaki Iitaka from the RIKEN Advanced Science Institute in Wako.


Figure 1: Traces of the positions of silane and hydrogen molecules over time at 32 GPa, obtained from molecular dynamics calculations. Hydrogen atoms at tetrahedral (white) and octahedral (red) sites are shown. Silicon atoms at so-called ‘face-centered cubic’ sites are shown by gray spheres.
Copyright : 2010 The American Physical Society

Iitaka, along with colleagues from the Institute of High Performance Computing in Singapore and the University of Saskatchewan in Canada, recently uncovered the physical basis underlying a newly discovered behavior of hydrogen molecules under high pressure[1].

This behavior was observed in a complex of hydrogen molecules, and hydrogen bound to silicon, which is called silane. Silane’s hydrogen atoms are under so-called 'chemical compression' by virtue of their being part of a chemical bond. In 2009, physicists found that the vibrational frequency of hydrogen molecules in silane–hydrogen complexes fell as the applied pressure rose. This anti-correlation was the opposite of previous observations of high-pressure hydrogen.

Iitaka and colleagues modeled the system using molecular dynamics simulations. They first optimized the relative arrangement of hydrogen and silane molecules inside a unit cell, finding that the hydrogen molecules tend to sit at octahedral and tetrahedral sites (Fig. 1). They then computed the vibrational frequencies of the hydrogen molecules, and found two groups of vibrational modes, one at high energy and one at low energy.

The frequencies of the lower-energy group decreased monotonically as applied pressure increased. However, the frequencies of the higher-energy group increased with pressure until about 20.1 giga Pascals (GPa), after which they fell. This reproduced the experimentally observed anti-correlation between vibrational frequency and applied pressure, indicating that the simulation was accurate.

The simulations also revealed that this rise and fall in frequencies resulted from interactions between hydrogen and silane molecules. These interactions resulted from the overlap between the filled electron orbitals of one molecule and the empty orbitals of the other molecule. This overlap stabilizes the system, and its strength depends on the distance between the molecules. This distance, in turn, depends on the applied pressure.

The simulation results are another glimpse into the exotic physics that underpins the high-pressure regime, according to Iitaka. “We have shown that there is much more interesting new physics and chemistry to be explored in the world of high pressure.”

The corresponding author for this highlight is based at the Computational Astrophysics Laboratory, RIKEN Advanced Science Institute.

Journal information

[1] Yim, W.-L., Tse, J.S. & Iitaka, T. Pressure-induced intermolecular interactions in crystalline silane-hydrogen. Physical Review Letters 105, 215501 (2010).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6495
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Airborne thermometer to measure Arctic temperatures
11.01.2017 | Moscow Institute of Physics and Technology

nachricht Next-generation optics offer the widest real-time views of vast regions of the sun
11.01.2017 | New Jersey Institute of Technology

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: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Solar Collectors from Ultra-High Performance Concrete Combine Energy Efficiency and Aesthetics

16.01.2017 | Trade Fair News

3D scans for the automotive industry

16.01.2017 | Automotive Engineering

Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs

16.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>