Single Beam Atomic Absorption Spectrophotometer:

A simplified sketch of a single beam flame atomic absorption spectrophotometer is dispaly in Figure. It consists of hollow cathode lamp (HCL), a radiation source, and flame as an atomisation device, a photomultiplier detector, a monochromator, and a recording system. A HCL radiation is chopped to eliminate the background signal arising from the radiation emitted through the sample itself and focused on the atomic vapour produced through the atomiser and then directed to the monochromator where the atomic line of interest is isolated.

Figure: Schematic diagram of a single beam flame atomic absorption spectrophotometer

The electronic amplifier is synchronised along with the chopper so in which the signal component produced through emission from the sample is not detected. The attenuation of the source radiation through the analyte atomic vapour is detected by the photomultiplier. A blank is aspirated within the flame and the transmittance is adjusted to 100 percent.