Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Polarizers May Enhance Remote Chemical Detection

13.03.2009
Chemists can analyze the composition of a suspected bomb -- without actually touching and possibly detonating it -- using a technique called laser-induced breakdown spectroscopy, or LIBS.

The tool is also commonly used for "stand-off" detection in such harsh or potentially dangerous environments as blast furnaces, nuclear reactors and biohazard sites and on unmanned planetary probes like the Mars rovers.

Information provided by LIBS, however, is sometimes clouded by interfering signals caught by the spectroscope -- and eliminating the background can be expensive. But a group of chemists at the University of Illinois at Chicago reports that equipping LIBS with a polarizing filter can do the job at a lower cost and probably with equal or greater sensitivity than the tools presently in use.

Robert Gordon, professor and head of chemistry at UIC, became interested in polarized light after reading books by cosmologist Brian Greene that described a slight polarization of the cosmic microwave background left over from the Big Bang. Out of curiosity, Gordon had his lab group zap a crystal of silicon by firing pairs of near-infrared laser pulses at 80 femtoseconds -- or 80 millionths of a billionth of a second. This "mini-Big Bang-like" laser ablation caused a brief spark, or plasma, that gave off ultraviolet light, which the group checked for polarization.

"We thought we'd see maybe a few percent polarization," said Gordon. "But when we saw 100 percent, we were totally astonished."

The spectrum of light they studied, similar to the rainbow a prism creates when held up to sunlight, includes a series of lines that are the hidden signatures of chemical elements. To get rid of the background spectrum and focus just on the element lines, current LIBS use a time-resolved method that works like a camera shutter by snapping at nanosecond speeds. Gordon's group discovered that by eliminating the shutter and instead using a rotating polarizer, they could filter out the background and focus on the lines.

"The polarizer costs just pennies, whereas a time-shutter is a very expensive component," Gordon said. "By simply putting a polarizer in a detector and rotating it to get maximum signal-to-noise ratio, you can improve the quality of the signal effortlessly and fairly cheaply."

Gordon said there is still basic work that needs to be done to answer why the light gets polarized. He said that varying the angle and the intensity of the laser pulses used to ablate the sample material may provide additional ways to enhance LIBS.

Gordon and his coworkers first reported their findings in the Feb. 15 issue of Optics Letters and will present their results at the Conference on Lasers and Electro-Optics May 31-June 5 in Baltimore.

Gordon's coworkers include postdoctoral research associates Youbo Zhao and Yaoming Liu, doctoral student Sima Singha, and former undergraduate Tama Witt.

Funding came from the National Science Foundation and the U.S. Air Force Research Laboratory Materials and Manufacturing Directorate.

Paul Francuch | Newswise Science News
Further information:
http://www.uic.edu

More articles from Life Sciences:

nachricht Stiffness matters
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown 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: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>