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LA-ICP-AES using a high resolution fiber optic interferometer

Combining state-of-the-art optics with established spectrometry, Ames Lab researchers are improving the resolution of portable spectrometers to make detailed characterization at some sites easier and less costly.

"We're filling a niche in field analysis capabilities left by other spectrometry systems,"says Ames Lab's David Baldwin, principal investigator for the new interferometric spectrometer. "When you need to distinguish between isotopes in the field, it will be nice to have our cheaper, portable optical spectrometer."

To create the new spectrometer, Ames Lab scientists borrowed two devices from the fiber optic communications industry. An acousto-optic tunable filter and a fiber-optic Fabry-Perot interferometer allow the new spectrometer to be compact for portability and have high enough resolution to distinguish the small differences between radioactive isotopes. Existing systems capable of such isotopic identification are too large, expensive and delicate for effective field operation.

Developing this technology to analyze environmental samples, the researchers combined the new spectrometer with laser ablation sampling and another technique developed at Ames Lab, inductively coupled plasma-atomic emission spectroscopy (ICP-AES). An established analytical tool, ICP-AES brings to the new spectrometry system its capabilities for rapid, sensitive detection of multiple elements with minimal sample preparation.

The whole combination will allow analysis of heavy metals and radioactive isotopes in the field where portability is important. While laboratory development proceeds, planning is underway to use the new system for testing samples at other DOE sites. Interactions are also being developed with commercial contacts who have expressed interest in the technology's future potential.



  • Better Resolution of Details - The interferometric spectrometer can distinguish the small differences between isotopes of radioactive elements such as uranium, thorium and plutonium. The system can also detect isobars (different elements that have the same atomic mass) that are not distinguishable with traditional mass spectrometric techniques.
  • Field-Operational - Smaller and more portable than other spectrometers with similar capabilities, this system allows on-site analysis where traditionally not available.
  • Less Costly Analysis - Offering immediate on-site results with a less expensive system, the interferometric spectrometer cuts traditional characterization costs.
  • Continuous, Easy Sampling - Small sample size, minimal preparation required and continuous remote sampling with laser ablation eases the often complex and hazardous sampling process.
  • Reliable, Accepted Technique - Based upon a spectrometry technique (ICP-AES) that is already well-established as accurate and reliable, this system offers a high level of acceptance and confidence.



With a remarkable combination of small size, affordability and high sensitivity, Ames Lab's new interferometric ICP-AES spectrometer should make detailed field testing possible in areas where traditional methods lack the required selectivity and portability.



David Baldwin, e-mail:, phone: (515) 294-2069