Chapter 7 
   Introduction to Atomic 
      Spectroscopy 
                                 Overview 
      •  In atomic spectroscopic methods, the analyte must 
         be converted into the appropriate chemical form to 
         emit or absorb radiation. 
      •  Almost always this involves converting the analyte 
         into free atoms, although occasionally spectroscopic 
         transitions of ions are used. 
      •  Samples for atomic spectrochemical analysis may 
         be in the form of liquids, solids, or gases. Most 
         commonly, sample preparation steps produce an 
         analytical sample that is a solution.  
      •  Thus the sample presentation system has a complex 
         task to perform in order to convert analyte species in 
         solution into vapor phase free atoms.  
      •  This usually entails the application of heat to break 
         up molecules into their component atoms.  
      •  The general routes for introducing solution samples 
         into flame and plasma atomization devices are 
         summarized in the Figure   
  Plasma and flame sample introduction schemes for solutions  
           Atomization Devices 
  • The sample container in which the 
    spectroscopic measurements are made is 
    usually a hot gas or an enclosed furnace.  
  • Flames, plasmas, electrical discharges (arcs 
    and sparks), and electrically heated furnaces 
    (electrothermal devices) are commonly used.  
    – Flames are formed by combustion of an oxidant 
     and a fuel, 
    –  whereas plasmas are partially ionized gases 
     maintained either by an electrical discharge or by 
     coupling to a microwave or RF field.  
    – An arc is a continuous electrical discharge 
     between conducting electrodes, while a spark is 
     an intermittent discharge.