Abstract

Over the last 5-6 years, efforts to employ the SP-LIF technique to measure atmospheric OH have met with two major problems. The first has involved the in situ production of OH by the UV probe laser itself. This can occur when atmospheric O₃ absorbs UV laser radiation and thereby produces O(′D) atoms. O(′D) in turn rapidly reacts with H₂O to produce two OH radicals. Since the detection of artificial OH necessarily depends on the availability of two-laser photons, the above problem can be greatly reduced in magnitude by reducing the laser energy density. Alternatively, the reaction of O('D) with H₂O can be short-circuited by using very narrow laser pulses. Both methods are now being used with modest success but at some price in detection sensitivity.

© 1983 Optical Society of America