Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Helium droplets offer new precision to single-molecule laser measurement
by Staff Writers
Washington DC (SPX) Jun 21, 2017


Schematic illustration of the alignment, induced by a 160 picosecond laser pulse (red), of an iodine molecule (purple) inside a helium droplet (blue). The iodine molecule is aligned vertically by the polarization direction of the alignment pulse, shown by the double-headed red arrow to the left. The degree of alignment is measured by a probe pulse (black) synchronized to the peak of the alignment pulse. Credit Henrik Stapelfeldt, Aarhus University

Chemical reactions necessarily involve molecules coming together, and the way they interact can depend on how they are aligned relative to each other. By knowing and controlling the alignment of molecules, a great deal can be learned about how chemical reactions occur.

This week in The Journal of Chemical Physics, from AIP Publishing, scientists from Aarhus University in Denmark and the Institute of Science and Technology in Austria report a new technique for aligning molecules using lasers and very cold droplets of helium.

This new method aligns molecules more sharply than is possible for the essentially isolated molecules of those in the gas phase. This is due to the fact that a molecule embedded in a very cold droplet shares the same low temperature as the droplet itself, a mere 0.4 kelvins, or -272.75 degrees Celsius. It is only rarely possible to obtain such low temperatures for molecules in the gas phase, so this technique promises to open up a significant new regime for study.

The method utilizes a pair of laser pulses in what's called a pump-probe method. The first pulse aligns the single molecule once it has been deposited into a helium droplet. The second laser pulse, the probe pulse, is used to determine the alignment, blasting the molecule apart and separating it into ions. The ions fly off at specific angles and can be detected using a camera coupled to a computer.

"Being able to control the alignment of large molecules is no simple feat," Henrik Stapelfeldt of Aarhus University said, "because as molecules grow in size it becomes increasingly difficult to get them into the gas phase and cool them."

The investigators studied three systems: iodine (I2) molecules, which have a simple linear dumbbell shape, and two more complex molecules consisting of benzene rings with either iodine or bromine atoms attached to the ring. In all three cases, they achieved strong alignment of a single molecule embedded in a cold helium droplet with the two-pulse technique.

Because I2 has a simple linear shape, the investigators were better able to compare their experimental results to theoretical predictions. This revealed that the laser-induced alignment of molecules in helium droplets was essentially identical to that in the gas phase, as long as the alignment was done adiabatically, or gradually with respect to the molecules' responses.

To carry out adiabatic alignment, the first laser pulse is turned on more slowly than the inherent rotational period of the molecule being studied. This allows a freely rotating iodine molecule, say, to strongly align with the laser's polarization axis, in much the same way that a compass needle aligns with the magnetic field of the Earth.

Future studies will focus on aligning larger, more complex molecules in these cold helium droplets, allowing scientists to watch chemical reactions unfold in real time. Stapelfeldt explained that it may be possible to align molecules as large as proteins.

"Helium droplets offer unique possibilities," he said, "for building tailor-made molecular complexes, thus broadening the scope of systems that can be studied."

The article, "Strongly aligned molecules inside helium droplets in the near-adiabatic regime," is authored by Benjamin Shepperson, Adam S. Chatterley, Anders A. Sondergaard, Lars Christiansen, Mikhail Lemeshko and Henrik Stapelfeldt. The article will appear in The Journal of Chemical Physics June 13, 2017 [DOI: 10.1063/1.4983703].

TECH SPACE
New waterproofing and antifouling materials developed by Swansea Scientists
Swansea UK (SPX) Jun 16, 2017
'Green' project led by Swansea scientists could replace more expensive and hazardous materials used for waterproofing and antifouling/fogging. New materials have been developed by scientists in the Energy Safety Research Institute (ESRI) at Swansea University which is nontoxic, economical and shows promise to replace more expensive and hazardous materials used for waterproofing and antifou ... read more

Related Links
American Institute of Physics
Space Technology News - Applications and Research


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

TECH SPACE
Russia launches space freighter to ISS

To Be or Not to Be: At 20 ISS Goes Strong, But for How Long

Bread Me Up, Scotty: Crumb-Free Pastries Coming to the ISS

NASA Prepares for Future Space Exploration with International Undersea Crew

TECH SPACE
Proton returns to flight with US satellite after 12 month hiatus

NASA awards Universal Stage Adapter contract for SLS

Russian rocket returns to service with launch of US satellite

Ariane 5 launches its heaviest telecom payload

TECH SPACE
Walkabout Above 'Perseverance Valley'

Hot rocks, not warm atmosphere, led to relatively recent water-carved valleys on Mars

Opportunity Surveying the spillway into Perseverance Valley

Window to a watery past on Mars

TECH SPACE
Moon or Mars - humanity's next stop

China's space station to help maintain co-orbital telescope

Seeds of 5,000-year-old tree bud after returning from space

What China's space ambitions have to do with politics

TECH SPACE
Jumpstart goes into alliance with major aerospace and defence group ADS

Thomas Pesquet returns to Earth

Propose a course idea for the CU space minor

Leading Global Air And Space Law Group Joins Reed Smith

TECH SPACE
Octopus inspires S. Korea 'breakthrough' adhesive patch

Oyster shells inspire new method to make superstrong, flexible polymers

A more sustainable way to refine metals

Recycled tires create stronger concrete

TECH SPACE
Astronomers Explain Formation of Seven Exoplanets Around TRAPPIST-1

OU astrophysicist identifies composition of Earth-size planets in TRAPPIST-1 system

Flares May Threaten Planet Habitability Near Red Dwarfs

The Art of Exoplanets

TECH SPACE
A whole new Jupiter with first science results from Juno

First results from Juno show cyclones and massive magnetism

Jupiters complex transient auroras

NASA's Juno probe forces 'rethink' on Jupiter




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement