Abstract
Continuous wave mid-infrared radiation at 3.36 μm (power ≈ 18 μW) has been produced by difference frequency generation of the fundamental of a YAG laser at 1064 nm (220 mW) with a fibre pigtailed DFB diode laser operating at 1560 nm (50 mW) in periodically poled lithium niobate. The idler radiation has been used to make real-time measurements of ambient methane present in our laboratory using wavelength modulation spectroscopy via the P(4) multiplet transitions within the ν 3 band. We demonstrate a minimum detectable concentration of 47 ppb over a path length of 0.71 m in a 1 s observation time. Measurements of the pressure broadening and shift parameters for these lines are presented for methane in the presence of air, nitrogen and argon.
Original language | English |
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Pages (from-to) | 102-108 |
Number of pages | 7 |
Journal | Chemical Physics Letters |
Volume | 399 |
Issue number | 1-3 |
DOIs | |
Publication status | Published - 21 Nov 2004 |