Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Physicists' findings about helium could lead to more accurate temperature, pressure measurements

Vial of glowing untrapure helium.  Image by Jurii
Vial of glowing untrapure helium. Image by Jurii

Abstract:
In the May 7 edition of Physical Review Letters, a journal of the American Physical Society, an international team led by University of Delaware researchers reports new findings about helium that may lead to more accurate standards for how temperature and pressure are measured.

by Tracey Bryant

Physicists' findings about helium could lead to more accurate temperature, pressure measurements

Newark, DE | Posted on May 19th, 2010

In the article, highlighted as an "Editor's Suggestion" by the journal, the scientists provide a new theoretical computation of the force acting between a pair of helium atoms, referred to as "pair potential," that is more accurate than any published to date.

Krzysztof Szalewicz, professor in the UD Department of Physics and Astronomy, led the study, which involved Wojciech Cencek, a postdoctoral researcher at UD, and colleagues from the University of Warsaw and Adam Mickiewicz University in Poland, and the University of Oslo in Norway.

Most of us know helium as a gas for filling party balloons or for making your voice temporarily sound like a cartoon character's. But this element named for the sun is used in lasers for eye surgery, to cooling agents in nuclear reactors.

Helium has a number of characteristics that make it special, Szalewicz says. It is the most stable of all the elements and has the lowest boiling point. It becomes a fluid at temperatures close to absolute zero while most other materials are a solid. In fact, helium is a liquid even at absolute zero and becomes a solid only at high pressure.

Helium is the only substance that exhibits superfluidity, and it will not burn or react with other elements, which is one reason why it is used as a pressurizing agent for liquid fuel rockets in space exploration, among many other applications.

"Of all the elements, helium is closest to the ideal gas," Szalewicz says. "Two helium atoms form the weakest bound diatomic molecule. All the properties of temperature, for example, which is a measure of the kinetic energy of particles in matter, can be modeled if the force acting between a pair of helium atoms is known.

"This has been the subject of extensive activity," Szalewicz notes, "as accurate knowledge of the pair potential of helium is of importance in several branches of science, including low-temperature condensed matter physics, spectroscopy, and metrology, which is the science of measurement."

The research team used complex numerical techniques to compute several physical effects in the helium pair potential which are rarely considered in molecular physics. These effects include couplings of the electronic and nuclear motions, contributions due to Einstein's special relativity, and the so-called quantum electrodynamics contributions due to the interaction of the electrons with the electromagnetic field.

The scientists predict that the binding energy of two molecules of helium, chemically referred to as a "dimer," is 6,790 times smaller than the potential depth, and the average separation between the atoms is 47 angstroms compared to the typical chemical bond length of about 1 angstrom. The estimated uncertainties of the theoretical results are an order of magnitude smaller than the best experimental ones, they report.

The thermophysical properties of gaseous helium computed from this potential now will be used to calibrate the apparatus for measuring properties such as viscosities or the speed of sound.

"These calculations should lead to new, better standards for quantities such as temperature or pressure," Szalewicz says. "Continuous improvement of metrology standards is important for progress in experimental science, as well as in many industrial applications."

The research was supported in part by grants from the National Institute of Standards and Technology and the National Science Foundation.

####

For more information, please click here

Contacts:
Phone: (302) 831-2792

Copyright © University of Delaware

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Possible Futures

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Academic/Education

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Haydale Announces Collaboration Agreement with Swansea University’s Welsh Centre for Printing and Coatings (WCPC) July 12th, 2014

STFC takes delivery of the 100th Hitachi Tabletop SEM in the UK July 3rd, 2014

Innovation Management and the Emergence of the Nanobiotechnology Industry July 1st, 2014

Discoveries

Iranian Scientists Produce Cobalt–Alumina Ceramic Nano Inks August 1st, 2014

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

Taking the guesswork out of cancer therapy: New molecular test kit predicts patient’s survival and drug response August 1st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Announcements

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Tools

Keysight Technologies Begins Operations August 1st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Analytical solutions from Malvern Instruments support University of Wisconsin-Milwaukee researchers in understanding environmental effects of nanomaterials July 30th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE