High-sensitivity simultaneous HNO3 and NH3 monitor using continuous wave quantum cascade laser IR absorption

Description

Aerosols play an important role in influencing the composition of the atmosphere, climate forcing, and human health. Secondary particles are formed and grow via gas to particle conversions in the atmosphere, including nucleation and condensation. We have developed a highly sensitive infrared absorption spectrometer using the latest developments in quantum cascade laser spectroscopy and an inlet system to enable quantitative and sensitive simultaneous measurements of gaseous nitric acid and gaseous ammonia, both of which are key aerosol precursors. The particle phase is measured using the Aerodyne aerosol mass spectrometer, a chemically speciated mass-based aerosol instrument. Measurements of nitric acid, ammonia, and particle ammonium nitrate will enable a better understanding of secondary aerosol formation and transformation in the atmosphere. These measurements will provide valuable data inputs for atmospheric models that predict the role of aerosols on radiative forcing and future climate. In this poster we describe the latest advances in instrument development and measurement precision for combination of HNO3 and NH3 that provide measurement capability at the low part-per-trillion levels for both species.