Atomic fluorescence spectrometry The mercury analyzers as a detectors use a cold vapor atomic fluorescence spectrometry method (CVAFS). In the CVAFS, light from small mercury vapor lamp is shined through a guartz flow cell that contains mercury in a stream of argon carrier gas. This light excites the mercury atoms which subsequently emit more light. The light emitted by the mercury atoms passes through the filter (254 nm) and into a photomultiplayer tube (PMT) which converts the light into an electrical signal. The amount of light emitted by the mercury vapour is proportional to the amount of mercury passing  through the cell. The atomic fluorescence detection method needs very high stability light stream. This stabilization is realised by the double beam method. UV-light is generated by the electrodeless mercury discharge lamp (EDL). Additionaly the optical cell is thermally stabilized.