Monochromators:

You know in which the monochromators are the devices that could selectively gives radiation of a desired wavelength out of the range of wavelengths emitted through the source or emitted through analyte sample. In AAS, the monochromators chosen a given emission line and isolate it from other lines because of molecular band emissions and all non absorbed lines. A few of these lines originate from the filler gas in the hollow cathode lamp although some others are the spectral emissions of several sample components during atomisation. Most commercial AAS instruments use diffraction gratings as monochromators.