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Updated: Jun 19, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Far-infrared terahertz time-domain spectroscopy of flames
Abstract:
We present what is to our knowledge the first comprehensive far-infrared absorption measurement of flames. These measurements, covering the region of 7-88 wave numbers (0.2-2.65 THz) are only now made possible by the technique of terahertz time-domain spectroscopy. We observe a large number of absorption lines-including those of water, CH, and NH(3)-in a stationary, premixed, propane-air flame. The absorption strength permits the determination of species concentration along the beam path. The f lame temperature is determined by comparison of the relative strengths of the water vapor lines.
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