Atomic Spectroscopy 
                                           Atomic Spectra 
  •  Electron excitation                                                energy                                   n = 1 
       – The excitation can occur at                                       ∆E                                    n = 2 
           different degrees                                                                                     n = 3, 
             • low E tends to excite the outmost                                                                 etc. 
                e-’s first 
             • when excited with a high E (photon 
                of high v) an e- can jump more 
                than one levels 
             • even higher E can tear inner e-’s                                                               4f 
                away from nuclei                                                  n=4                          4d 
                                                                                                               4p 
       – An e- at its excited state is not stable and tends to                                                 3d 
           return its ground state                                        gy                                   4s 
                                                                          r       n=3                          3p 
                 - jumped more than one energy levels because 
       – If an e                                                          ne                                   3s 
           of absorption of a high E, the process of the e-               E       n=2                          2p 
           returning to its ground state may take several steps, -                                             2s 
           i.e. to the nearest low energy level first then down to                n=1                          1s 
           next … 
                                        Atomic Spectra 
    •   Atomic spectra 
          – The level and quantities of energy                      energy                                n = 1 
                                     -                                ∆E 
            supplied to excite e ’s can be measured                                                       n = 2 
            & studied in terms of the frequency and                                                       n = 3, 
            the intensity of an e.m.r. - the                                                              etc. 
            absorption spectroscopy  
          – The level and quantities of energy 
                                      -
            emitted by excited e ’s, as they return to 
            their ground state, can be measured & 
            studied by means of the emission 
            spectroscopy                                                                                 4f 
          – The level & quantities of energy                                 n=4                         4d 
            absorbed or emitted (v & intensity of                                                        4p 
            e.m.r.) are specific for a substance                                                        3d 
                                                                      gy                                4s 
                                                                      r      n=3                        3p 
          – Atomic spectra are mostly in UV                           ne                                 3s 
            (sometime in visible) regions                             E      n=2                         2p 
                                                                             n=1                         2s 
                                                                                                         1s 
                             Atomic spectroscopy 
       •   Atomic emission 
            – Zero background (noise)  
            
            
            
            
       •   Atomic absorption 
            – Bright background (noise) 
            – Measure intensity change 
            – More signal than emission 
            – Trace detection