Two dye materials that display near infrared absorption bands have been syn
thesised and applied successfully to the optical sensing of ammonia vapour.
Methyl- and ethyl-derivatives of a 5-(4'-dialkylaminophenylimino)quinolin-
8-one copper(II)perchlorate complex were immobilised in a thin-film PVC mat
rix coated on a 600 mu m optical fibre. Evanescent wave absorption was used
to interrogate the dye under exposure to 10-100 ppm ammonia in nitrogen ca
rrier gas. The immobilised dyes were found to show large absorption bands a
t 740 and 770 nm for the methylated and ethylated forms, respectively. The
peak maxima were monitored in real-time using a CCD array microspectrometer
. The response and recovery times were found to be in the order of seconds
and the reversibility excellent. (C) 1998 Elsevier Science S.A. All rights
reserved.