Real-Time, Ultrasensitive Ammonia Sensor

Ammonia is the dominant species in the troposphere, and is known to rapidly associate with various acidic compounds to form aerosols. The equilibria of gaseous ammonia with acids as well as aqueous droplets is still not fully understood, especially at lower temperatures and concentrations. Detection of NH3 at ppt to ppb concentration levels is still difficult to achieve with established methods, especially with the added requirement that the temporal resolution be adequate for a number of atmospheric correlation studies. This project will develop a fully automated instrument that can accurately monitor ammonia with ppb resolution in 1-second. This will be accomplished by developing a new, fieldable spectrometer that is based on combining a recently available solid state laser source with an ultra-sensitive spectroscopic detection method. In Phase I, the core sensor breadboard system will be constructed, tested, and used to perform measurements on ammonia samples. Additionally, optimum spectral transitions for ammonia monitoring will be identified, and a fast response sampling system will be designed. Finally, designs for a ruggedized Phase II system will be identified. Commercial Applications and Other Benefits as described by the Applicant: The markets for continuous ammonia monitoring systems include emissions monitoring, atmospheric research, and cooling-system leak detection . Potential installation sites include the thousands of sources of significant ammonia emissions, including dairies, feed lots, farms, and urban environments. Additionally, the sensor will be suitable for numerous atmospheric monitoring applications, including studies of the role of ammonia in aerosol formation and chemistry.