[China Instrument Network Instrument Development] Water vapor content in high-purity gas is an important parameter in the semiconductor industry. Even residual ppbv in the gas (on the order of one-billionth in volume) will have an impact on product quality. The gas has more abundant characteristic lines in the mid-infrared region, and it is necessary to detect the moisture content in this region. The rapid development of wide tuning range, high output power, and narrow linewidth quantum cascade lasers has promoted the development of infrared spectroscopy technology in this region.
(Image from the Internet, invaded)
For the first time, the Institute of Optoelectronics used a 5.2 μm tunable quantum cascade laser in the mid-infrared waveband, established a detection device for trace moisture based on continuous cavity ring-down spectroscopy, and carried out trace moisture detection experiments. Through Alan's analysis of the noise level of the system, the optimal number of optical ringdown signals was determined to be 602. The water vapor absorption spectrum near 1918 cm-1 was measured at normal pressure and room temperature, and the trace moisture concentration in high purity nitrogen was measured. The detection result was consistent with the nominal value. The detection sensitivity was analyzed, and the detection sensitivity of water vapor reached 24.8 ppbv when the cavity mirror reflectivity was 99.93%. The analysis results show that the mid-infrared highly sensitive trace gas detection technology has a good application prospect in the fields of industrial monitoring, environmental detection and medical diagnosis.
Related research results were published in Spectroscopy and Spectral Analysis.
(Original Title: Advances in Research on Trace Moisture Detection in Optoelectronics)