The measurement of tropospheric OH by long path absorption 1. Instrumentation

摘要: The determination of the concentration OH in Earth's troposphere is fundamental importance to an understanding chemistry lower atmosphere. Many experiments measure have been performed recent years; very few these produced significant results. In particular, because extremely low amount clean (several tenths parts per trillion by volume at summertime local noon), none attained sensitivity limit necessary test photochemical theories and its temporal behavior. Described here experiment utilizing a laser source high resolution ultraviolet absorption spectroscopy environment measured approximately 5 × 105 cm−3 (0.01 pptv) with integration time several minutes. This substantially below predicted noontime concentrations should be enough provide rigorous hydroxyl formation. paper describes instrumentation developed make measurements.