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Principles of Operation Teledyne API - T100 UV Fluorescence SO2 Analyzer
286
13.1.7.2. PMT OPTICAL FILTER
The PMT used in the T100 reacts to a wide spectrum of light which includes much of
the visible spectrum and most of the UV spectrum. Even though the 214 nm light used
to excite the SO
2
is focused away from the PMT, some of it scatters in the direction of
the PMT as it interacts with the sample gas. A second optical band pass filter placed
between the sample chamber (refer to Figure 13-2) and the PMT strips away light
outside of the fluorescence
spectrum of decaying SO
2
* (refer to Figure 13-5) including
reflected UV form the source lamp and other stray light.
LAMP OUTPUT
(Arbitrary Untis)
10
5
10
4
10
2
10
3
10
1
1
100
200
300
400 500
WAVELENGTH (nm)
0
213.9
330.3
SO
2
* FLUORESCENT
SPECTRUM
PMT OPTICAL FILTER
BANDWIDTH
Figure 13-5: PMT Optical Filter Bandwidth
06807C DCN6650