contents

The science behind "Eye of the Beholder"

"Eye of the Beholder," the photo on page 21, is an inside view of a vacuum chamber that will be used for laser-ablation, matrix-isolation studies of actinide metal atoms and ions with small gaseous molecules such as oxygen, nitrogen, carbon dioxide, and hydrogen.

The research is the postdoctoral project of Steve Willson of the Actinide Research and Development Group (NMT-11) and is sponsored jointly by Kirk Veirs of NMT-11 and Joe Baiardo of the Nuclear Materials Science Group (NMT-16).

Inside the vacuum chamber, a small actinide metal target is supported by a post inserted into the port through which the camera is looking (the post has been removed for the photograph).

A neodymium:yttrium aluminum garnet-or Nd:YAG-laser beam passing through the port where Greenbank has digitally added an eye is focused onto the surface of this metal target.

The resulting laser-induced plasma of metal atoms and ions are co-deposited with neon or argon and a small amount of reactant gas onto the mirrored copper surface visible in the center of the photograph. This surface is cooled to 6 Kelvins (six degrees above absolute zero) by a closed-cycle helium refrigerator. The resulting thin film contains the reaction products of the metal atoms and ions with the reactant gas frozen into the inert gas matrix. The reaction products are detected using infrared spectroscopy, which results in a series of vibrational bands.

Precise identification of the chemical formula of the reaction products is obtained by repeating the experiment with the same reactant gas containing a different mix of isotopes, which results in the vibrational bands shifting in predictable ways.

The chemical behavior of these reaction products are further studied by warming the matrix to a still chilly 10 to 35 K elvins, by photolysis of the products with ultraviolet light, or both.

Willson expects the system to be online this summer in the Plutonium Facility (PF-4), where it will be used to experimentally probe some of the simple reaction chemistry of actinide atoms with common atmospheric constituents. He designed the apparatus based on his graduate work with Lester Andrews at the University of Virginia and adapted it for safe operation with actinides and optimal use of the available space.

He anticipates that his research will be valuable for the exploration of some of the underlying processes that occur in larger systems. The data collected will provide a spectroscopic catalog that he and his sponsors hope will simplify the identification of actinide compounds in larger systems, with application for corrosion studies of actinide-containing components.

The components were fabricated by Art Montoya of the Chemistry Facilities Management Group (C-FM) in the TA-48 machine shop and welded by Johnny Quintana of the Weapons Materials and Manufacturing Group (ESA-WMM) at the main shop. During the design stage, Willson received assistance from John Morris of NMT-11.

Several adjustments made during the fabrication stage at the suggestion of Montoya improved the design and have been instrumental in an invention disclosure filed on one of the fabricated components.


NMT | LANL | DOE
Phone Book | Search | Help/Info

L O S  A L A M O S  N A T I O N A L   L A B O R A T O R Y
Operated by the University of California for the US Department of Energy

Questions? - Copyright © UC 1998-2000
- For conditions of use, see Disclaimer