This work was supported by National Science Foundation grant ATM-8615163, National Aeronautics and Space Administration grant NAG-I-697, and Environmental Protection Agency grant R81-3012.
Journal of Geophysical Research
Air -- Pollution -- Measurement, Air -- Pollution -- Oregon, Hydroxyl group
Ambient HO measurements by low-pressure laser-excited fluorescence with chemical modulation, and supporting ozone and water-vapor data, are presented for periods in May and August 1987. The observed peak daytime ambient HO concentrations in Oregon are in the range (2.5 to 8) times106 molecules cm⁻³ and show small negative offsets due to photochemical interference. Direct measurements of the interference at fixed [O₃] give the dependence on ambient [H₂O] and on the modulating reagent [isobutane]. At ambient [O₃]=30 p.p.b. and 10 torr H₂O, with excitation and detection at a total pressure of 4 torr, the net interference is equal to [HO]=-1.3times10⁶ molecule cm⁻³.
Hard, T. M., Mehrabzadeh, A. A., Chan, C. Y., and O'Brien, R. J. (1992). FAGE measurements of tropospheric HO with measurements and model of interferences. Journal Of Geophysical Research, 97(D9), 9795-9817.