1. Origin of an Atomic Absorption Peak E2E2 E1E1  E = h Frequency Intensity Energy Transition Absorption Spectrum 1

2. Atomic Absorption for a Hydrogen Atom Electronic energy levels in a H atom 1s 2s 2p 3s 3p 3d The lowest energy state has the single electron in the 1s orbital 1s 1 2

3. A brief history of Atomic Absorption Spectrometry 1802 Wollastone - discovered black lines in Sun's spectrum which were subsequently investigated by Fraunhoffer (1823). Solar spectrum 3

4. A brief history of Atomic Absorption Spectrometry – 1820 Brewster - suggested black lines in solar spectrum due to absorption processes in Sun's atmosphere. – 1859 Kirchhoff and Bunsen - demonstrated Na D line absorption in visible spectra. 4

5. A brief history of AAS Hydrogen spectrum Solar spectrum Mercury spectrum Interpretation of Fraunhoffer lines in terms of atomic absorption by elements in the suns atmosphere 1859-1955 Astronomers use atomic absorption to estimate metal concentrations in atmospheres of stars. 5

6. What is AAS? ( AAS) Atomic Absorption Spectroscopy is: Quantitative technique Typical samples: low viscosity samples Generally uses to determine the amount of several metals (e.g. Cu, Fe, Zn, Mg) in the soil, blood, air, water, and food. Occasionally can be use as a qualitative technique (can indentify chemicals that are present) – 68 elements

7. In the electromagnetic spectrum, it uses the visible part to detect the presence of metals. Foundation of the technique: the absorption of the light energy that has the right wavelength causes the electrons from the sample to be promoted from a lower energy level to a higher energy level.