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diode array to measure the fluorescent light, could produce a vastly improved fluorescence
spectrometer.
There are however, some problems to be overcome in the use of the diode array, that arise from the low
sensitivity of the diode, compared with the normal photomultiplier tube. This low sensitivity is the
result of the high background noise level, which consists of 'fixed pattern' noise and integrated 'dark
current' (background signal). The fixed pattern noise comes from the many electronic components
contained in the entire electronic system, and will include noise from the detector electronics, data
acquisition, computer processing and display circuits. This source of noise can be largely removed by
digital background subtraction.
Figure 7.20
The Diode Array Fluorescence Spectrometer
Reprinted with permission from J. Wegrzyn, G. Patonay,
M. Ford and I. Warner, Anal. Chem., 62(17)(1990)1754,
Copyright 1990 American Chemical Society
The dark current noise arises from the thermal discharge of reverse bias on each diode. Fluctuations in
dark current are directly related to
