Applications and Optoelectronic Methods of Detection of Ammonia

This chapter describes applications of ammonia in agriculture, pharmaceutical and environmental industries and optoelectronic methods of its detection. In Section 2 the discovery, the chemical structure, reactivity and application of ammonia are reviewed. Applications in agriculture, cleaning products, pharmaceutical industries, beauty products, the benefits and dangers of ammonia to human health, environment and industrial processes are also discussed. Section 3 describes the rotational-vibrational molecular processes that cause the optical absorption of light in the infrared spectrum. The infrared and ultraviolet absorption spectra are also shown. Data relating to the absorption of light by ammonia at ultraviolet wavelengths is also shown. Existing optical ammonia gas detectionmethods that utilise lasers and broadband sources and the evanescent field of an optical fibre are described in Section 4. This includes a discussion of optical sources, optical fibers, gas cell designs and detectors that are used in optoelectronic gas sensing systems. In section 5, the limiting effects of fundamental noise sources, such as photon noise, resistor noise and optical source noise on sensor sensitivity are described. The selective performance of optoelectronic gas sensors is also discussed, i.e. the discrimination of the sensor to different gases.