Article ID Journal Published Year Pages File Type
1235862 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2007 8 Pages PDF
Abstract

We describe the hardware and software of the high-sensitive two-channel opto-acoustic spectrometer with a near infrared diode laser. A semiconductor TEC-100 laser with outer resonator generates a continuous single-frequency radiation in the range of 6040–6300 cm−1 with spectral resolution better that 10 MHz. The newly designed model of photo-acoustic cells in the form of a ring type resonator was used in the spectrometer, and the system allows the measurement of a weak absorption coefficient equal to 1.4 × 10−7 cm−1 Hz−1/2 with a laser radiation power of 0.003 W. The methane absorption spectra within a range of 6080–6180 cm−1 were measured with a spectral resolution of 10 MHz and the signal to noise ratio more than 103. Six hundred absorption lines were recorded, which is twice as many as in HITRAN-2004. The accurate measurements of the half-width and shift of methane unresolved triplet R3 of 2ν3 band permit us to determine values of the broadening and shift coefficients for CH4–air, CH4–N2, and CH4–SF6 mixtures.

Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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