PNNL

Abstract

The principal goal of Pacific Northwest National Laboratory's (PNNL’s) Infrared Technology for Advanced Sensors Project is to explore and develop the science and technology behind point and stand off infrared (IR) spectroscopic chemical sensors that are needed for detecting weapons proliferation activity. The primary use of the technology is to detect the chemical signatures associated with the production or use of chemical, biological, or nuclear weapons. In FY04 PNNL continued the development of a Shortwave Infrared (SWIR) point sensor based on optical Cavity Ringdown Spectroscopy (CRDS). During the year this instrument participated in 3 field tests, including the indoor UF6 release experiment which took place on the Hanford Site in Aug. 2004. The field tests demonstrated the robustness of CRDS as a fieldable technology for sensitive detection of airborne analytes. The instrument was altered from detecting ammonia with a detection limit of ~ 1 ppmv to detect hydrogen fluoride with a detection limit of ~ 3 ppbv. The differences in limits of detection between these two chemicals is accounted for by the relative differences in the absorption strength of the two molecules (with HF having a much larger absorption strength than ammonia). In addition to the field tests, the instrument underwent further refinement to improve long term stability. These enhancements resulted from improvements in both hardware and software. We outline all of these accomplishments in detail in the body of this report.