Detection of moisture content in high-purity ammonia by means of diode-laser spectroscopy

• Published in: Applied physics. B, Lasers and optics Vol. 90; no. 2; pp. 317 - 321
• Main Authors: Berezin, A.G., Nadezhdinskii, A.I., Ponurovskii, Y.Y., Stavrovskii, D.B., Vyazov, I.E., Kotkov, A.P., Ivanov, V.A., Grishnova, N.D., Polezhaev, D.M., Sidorov, V.A., Kotkov, D.A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.02.2008
• Subjects: Ammonia; Diodes; Engineering; Humidity; Lasers; Mathematical analysis; Moisture content; On-line systems; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Purification; Quantum Optics; Analytical Cell; Absorption Line; Water Concentration; Water Line; Reference Cell
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-007-2903-4

The aim of this work was the development of an as-simple-as-possible instrument for trace moisture concentration measurements in high-purity ammonia. A near-infrared diode-laser-based instrument has been applied to measure the humidity in a process of on-line detection of water in ammonia during industrial purification. The results of water concentration measurements were compared with alternative techniques (primarily dew-point detection) and good agreement was achieved. The long-term sensitivity of such a diode-laser-based instrument was estimated to be 5 ppm. The calculation of the water concentration from measurements of the integrated volume of water contained in the heavy fraction, extracted during the purification process, yields an even lower detection limit of less than 0.1 ppm, depending on the initial ammonia purity.