W. Armerding et al., OH MULTIPASS ABSORPTION - ABSOLUTE AND IN-SITU METHOD FOR LOCAL MONITORING OF TROPOSPHERIC HYDROXYL RADICALS, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 99(D1), 1994, pp. 1225-1239
OH multipass absorption is an absolute and spatially resolving method
for the in situ monitoring of tropospheric OH. The basis of the method
is differential optical absorption spectroscopy. The absorption path
in ambient air is folded within a 6 m White cell type multiple reflect
ion system with an open path setup. SO2, CH2O, and naphthalene are mea
sured at 308 nm simultaneously with OH by means of the first harmonic
of the laser radiation. NO2 can be measured using the fundamental at 6
16 nm, respectively. The detection limit of the reported instrument is
2-5 x 10(5) OH cm(-3) corresponding to a signal to noise ratio of bet
ter than one or two for a 1-min monitoring time dependent on the bound
ary conditions. The performance of the method is demonstrated by tropo
spheric OH measurements achieved during a field campaign at the Taunus
Observatory on the Kleiner Feldberg in the vicinity of Frankfurt/Main
.