Ambient Level Hydroxyl Radical (OH) Detection Using Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS) in an Open-Path Configuration

Brigham Young University, Provo UT

Investigators

Abstract

This project supports the development and testing of an open-path, broad band cavity-based absorption spectrometer (BBCEAS) to measure hydroxyl radicals (OH) at ambient concentrations in the atmosphere. Hydroxyl radicals are one of the most important oxidizing species in the lower atmosphere, controlling the atmospheric lifetimes of many gases and reacting with both natural and anthropogenic hydrocarbons leading to the production of pollutant ozone. If successful, this instrument will provide data that can be used to improve the accuracy of models so that there will be better agreement between modeled and experimentally measured concentrations of OH and volatile organic compounds (VOC) and their photooxidation products, such as ozone. In order to build the new instrument to quantify OH radical concentrations, an open-cavity design is required. The principal investigators will conduct experiments to characterize the effects of turbulence and aerosols as well as include the effects of horizontal wind on the quantification of OH using the open-cavity design. They will then interface a high-resolution spectrometer to the open cavity BBCEAS instrument and test the initial configuration of the instrument and spectrograph/detector in the atmospheric simulation chamber at BYU. If the instrument is able to achieve an adequate limit of detection (LOD), the next step will be to test it in the field and intercompare it with other methods for measuring OH in the atmosphere. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.