Mid-infrared trace gas analysis with single-pass fourier transform infrared hollow waveguide gas sensors.
A hollow core optical fiber gas sensor has been developed in combination with a Fourier transform infrared (FT-IR) spectrometer operating in the spectral range of 4000-500 cm(-1), enabling continuous detection of small volume gas-phase analytes such as CH(4), CO(2), C(2)H(5)Cl, or their mixtures at trace levels. Ag/Ag-halide hollow core optical fibers simultaneously serve as an optical waveguide for broad-band mid-infrared radiation and as a miniaturized absorption gas cell. Specifically, carbon dioxide, methane, and ethyl chloride as well as binary mixtures in a carrier gas were analyzed during exponential dilution experiments. In the studies reported here, the integration of an optical gas sensor with FT-IR spectroscopy provides excellent detection limits for small gas volumes ( approximately 1.5 mL) of individual analytes at a few tens of parts per billion (ppb, vol/vol) for carbon dioxide and a few hundreds of ppb (vol/vol) for methane. Furthermore, the broad-band nature of the radiation source and of the hollow core optical waveguide provides the capability of multi-constituent analysis in mixtures.
Kim
Seong-Soo
SS
Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, Georgia, 30332-0400, USA.
Menegazzo
Nicola
N
Young
Christina
C
Chan
James
J
Carter
Chance
C
Mizaikoff
Boris
B