Page 154 - An Introduction to Analytical Atomic Spectrometry - L. Ebdon
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Figure 6.2
Growth curve for manganese atomic fluorescence
at 280 nm.
6.2 Instrument Design
In some flame AFS systems, interference filters and solar blind photomultipliers have been used to
reduce the background, but usually a conventional monochromator is used. As in AAS, the source
signal is modulated so that the atomic fluorescence can be distinguished from atomic emission.
It has been shown that a high frequency of modulation of the electrodeless discharge lamp (e.g. 10
kHz) is advantageous. This frequency is well away from the low frequency of flame noise. If the
amplifier is 'locked-in' to this high frequency via a reference signal, an optimum signal-to-noise ratio is
achieved.
