Photodiode detectors, comparison photomultiplier

The first measurement we make when starting a fluorescence study is not usually a fluorescence measurement at all but the determination of the sample s absorption spectrum. Dual-beam differential spectrophotometers which can record up to 3 absorbance units with a spectral range of 200-1100 nm are now readily available at low cost in comparison to fluorimeters. The wide spectral response of silicon photodiode detectors has made them preeminent over photomultipliers in this area with scan speeds of a few tens of seconds over the whole spectral range being achieved, even without the use of diode array detection. 

As shown in the discussion above, there are a multiplicity of desirable and undesirable features of OID s that impact their general application as detectors in analytical atomic emission spectrometry. It is therefore appropriate to compare, in a critical and objective sense, the experimental figures of merit of these devices vis-a-vis the classical polychromator photomultiplier approach. These comparisons should be performed virtually on a continuing basis because of advances in performances, not only of the array detectors themselves but also in the associated spectroscopic excitation sources. An evaluation of the overall performance figures of merit of OID s when they are employed in conjunction with induction-coupled plasma excitation is of particular current interest because of the popularity that this source is attaining for the simultaneous determination of the elements at all concentration levels. In this paper we present such an evaluation for self-scanned, photodiode array detectors... 

The limited availability of affordable commercial RSSF instruments has been an important factor that has prevented the widespread application of RSSF spectroscopy to the study of biological systems. However, in the past year, a significant change in the availability of commercial instrumentation hats come about. There currently are at least five manufacturers of computerized rapid-scanning detector systems. The choices in commercial instrumentation range from a mechanically scanned system with a single photomultiplier detector to photodiode array detector systems. This review includes descriptions of the currently available commercial systems. Because the authors experience in the field of RSSF spectroscopy is limited to the use of diode array detector systems and because most of the commercial instruments have appeared on the market just within the past 12 months, it has not been possible to make detailed performance evaluations and comparisons of the new commercial systems. 

---