Multichannel advantage characteristics

There are several advantages to a tunable filter system. First, it is unnecessary to have a multichannel detector (for single-point measurements), since only one wavelength is being selected at a time. The size of the detector is also much more flexible, since spectral resolution of the system is not a function of the detector and input aperture as it is in a classical monochromotor, but rather limited only by the functional characteristics of the filter. Second, since focusing and dispersive elements are minimized the spectrometer could be made very small. Third, the entire spectrum does not need to be obtained the random access nature of the filter allows only the spectral features required for a measurement to be made. This can be a significant advantage for routine measurements. 

In the past, molecular luminescence spectrometry was always conducted with single channel systems involving a photomultiplier tube (PMT) as the detector. The availability of multichannel detectors with internal gain has provided a new powerful tool for luminescence measurements, and several types of applications have been reported (1-15). This paper is concerned with the application of an intensified diode array dynamic molecular fluorescence and chemiluminescence measurements. In this paper the types of measurements and analytical systems for which multichannel detectors are used in our laboratory are introduced. Next the specific IDA system used is presented along with important hardware and software considerations. Third, the characteristics of the IDA detector are reviewed to give some perspective about its influence on the quality of measurements. Finally, some typical applications to chemical systems are presented to illustrate the advantages of multichannel detection. 

In view of the resolution characteristics of an ED detector, spectral overlap interferences are much more common in ED-XRE than WD-XRF and require a more comprehensive correction procedure than the simple line ratio method often used in the latter technique. However, advantage can be taken of the digital form in which ED spectral data are accumulated in the multichannel analyzer, which offers information about peakshapes as well as intensity. For simple ED spectra, it may be possible to define a series of windows covering each fluorescence peak of interest (the region-of-interest approach). Peak intensities can then be determined by chaimel integration and a background correction applied by linear interpolation between the lowest and the highest channel of the window. For complex spectra, a more sophisticated approach is required, of which two have found widespread use. 

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