Detectors:

As the wavelengths of resonance lines fall within UV region, the most general used detector in atomic absorption spectrophotometry is photomultiplier (PM) tube whose output is fed to a readout system. The radiation received through the detector might originate not only from the selected resonance lines but also from the emission inside the flame. Thus, in addition to absorption signal intensity IA, the detector might receive signal intensity of (IA + S) whereas S is the intensity of emitted radiation from flame. In fact one needs only the signal intensity due to absorption, it is thus, significant to eliminate effects due to flame emission. This is achieved through modulating the emission from the emission line source using a mechanical chopper device.

Readout Devices

The readout systems involve meters, chart recorders and digital display meters. These days, therefore, microprocessor controlled systems are commercially available whereas everything could be completed through touch of a button. Modern instruments give a fast display of the experimental conditions, absorbance data, statistical values and calibration curves, etc.