Infrared signatures for remote sensing
PNL`s capabilities for infrared and near-infrared spectroscopy include tunable-diode-laser (TDL) systems covering 300--3,000 cm{sup {minus}1} at <10-MHz bandwidth; a Bruker Fourier-transform infrared (FTIR) spectrometer for the near- to far-infrared at 50-MHz resolution; and a stable line-tunable, 12-w cw CO{sub 2} laser. PNL also has a beam expansion source with a 12-cm slit, which provides a 3-m effective path for gases at {approximately}10 K, giving a Doppler width of typically 10 MHz; and long-path static gas cells (to 100 m). In applying this equipment to signatures work, the authors emphasize the importance of high spectral resolution for detecting and identifying atmospheric interferences; for identifying the optimum analytical frequencies; for deriving, by spectroscopic analysis, the molecular parameters needed for modeling; and for obtaining data on species and/or bands that are not in existing databases. As an example of such spectroscopy, the authors have assigned and analyzed the C-Cl stretching region of CCl{sub 4} at 770--800 cm{sup {minus}1}. This is an important potential signature species whose IR absorption has remained puzzling because of the natural isotopic mix, extensive hot-band structure, and a Fermi resonance involving a nearby combination band. Instrument development projects include the IR sniffer, a small high-sensitivity, high-discrimination (Doppler-limited) device for fence-line or downwind monitoring that is effective even in regions of atmospheric absorption; preliminary work has achieved sensitivities at the low-ppb level. Other work covers trace species detection with TDLs, and FM-modulated CO{sub 2} laser LIDAR. The authors are planning a field experiment to interrogate the Hanford tank farm for signature species from Rattlesnake Mountain, a standoff of ca. 15 km, to be accompanied by simultaneous ground-truthing at the tanks.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 10161758
- Report Number(s):
- PNL-SA-24200; CONF-9404162-8; ON: DE94014222; TRN: 94:013618
- Resource Relation:
- Conference: 1994 chemical analysis by laser interrogation of proliferation effluents (CALIOPE ITR) interim technical review,Livermore, CA (United States),26-28 Apr 1994; Other Information: PBD: Apr 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
HANFORD RESERVATION
STORAGE FACILITIES
AIR POLLUTION MONITORING
CARBON TETRACHLORIDE
OPTICAL RADAR
FIELD TESTS
TECHNOLOGY ASSESSMENT
INFRARED RADIATION
NEAR INFRARED RADIATION
ABSORPTION SPECTROSCOPY
METHYLENE CHLORIDE
CHLOROFLUOROCARBONS
EXPERIMENTAL DATA
053003
540120
CHEMICAL AND THERMAL EFFLUENTS
CHEMICALS MONITORING AND TRANSPORT