Investigation of SO3 absorption line for in situ gas detection inside combustion plants using a 4-μm-band laser source

A Tokura; O Tadanaga; T Nishimiya; K Muta; N Kamiyama; M Yonemura; S Fujii; Y Tsumura; M Abe; H Takenouchi; K Kenmotsu; Y Sakai

doi:10.1364/AO.55.006887

Investigation of SO₃ absorption line for in situ gas detection inside combustion plants using a 4-μm-band laser source

Appl Opt. 2016 Sep 1;55(25):6887-92. doi: 10.1364/AO.55.006887.

Authors

A Tokura, O Tadanaga, T Nishimiya, K Muta, N Kamiyama, M Yonemura, S Fujii, Y Tsumura, M Abe, H Takenouchi, K Kenmotsu, Y Sakai

PMID: 27607263
DOI: 10.1364/AO.55.006887

Abstract

We have investigated 4-μm-band SO₃ absorption lines for in situSO₃ detection using a mid-infrared laser source based on difference frequency generation in a quasi-phase-matched LiNbO₃ waveguide. In the wavelength range of 4.09400-4.10600 μm, there were strong SO₃ absorption lines. The maximum absorption coefficient at a concentration of 170 ppmv was estimated to be about 3.2×10^-5 cm^-1 at a gas temperature of 190°C. In coexistence with H₂O, the reduction of the SO₃ absorption peak height was observed, which was caused by sulfuric acid formation. We discuss a method of using an SO₃ equilibrium curve to derive the total SO₃ molecule concentration.