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C hapter 2 Atomic Emission Spectroscopy

C hapter 2 Atomic Emission Spectroscopy. Chapter 2 Atomic Emission Spectroscopy. 2.1. Introduction to Optical Methods 2.2. Fundamentals of AES 2.3. Instrumentation 2.4. Analytical Methods of AES 2.5. Control of Analytical Interferences. 2.1. Introduction to Optical Methods.

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C hapter 2 Atomic Emission Spectroscopy

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  1. Chapter 2 Atomic Emission Spectroscopy

  2. Chapter 2 Atomic Emission Spectroscopy 2.1. Introduction to Optical Methods 2.2. Fundamentals of AES 2.3. Instrumentation 2.4. Analytical Methods of AES 2.5. Control of Analytical Interferences

  3. 2.1. Introduction to Optical Methods • The Nature of Radiant Energy • Spectral Regions • Interaction of Radiation with Atom • Instrumentation

  4. 2.1.1 The Nature of Radiant Energy The Duality of Light: • Wave properties • Reflection • Scattering • Refraction • Diffraction (2.1) - V frequency, C velocity of light ,  wavelength, v wave number

  5. 2. Particular proper ( the Energy of a photon) (2.2) Where his Planck’s constant, h=6.6256×10-34 J.s

  6. 2.1.2 Spectral Regions

  7. 2.1.3 Interaction of Radiation with Atoms • Emission Atom (high excited state) → Atom (lower excited state) + h • Absorption Atom (ground state) + h → Atom (high excited state) • Fluorescence Atom (ground state) + h → Atom (high excited state)  Atom (lower excited state) + hF

  8. 2.1.4 Instrumentation ⑴ LightSource 1. The main components ⑵ Sample cell ⑶ Polychromator or Monochromator ⑷ Detector

  9. 2. Atomic spectrometry system

  10. 2.2. Fundamentals of AES 2.2.1. The Energy Level Structure of an Atom

  11. 2.2. Fundamentals of AES Atomic Emission Processes ⑵ Emission ⑴ Excitation

  12. Example 1.

  13. Example 2.

  14. 2.2.2 The Atomic Spectrum • ⑴ The wavelength of a line depends on the energy difference of two states ⑵The intensity of the line depends on the number of atoms at higher level

  15. An atomic emission spectroscopic method need: • Enough high temperature environment to produce enough free atoms and there are enough atoms at higher excited states • A dispersion device to form a Spectrum • A detector to convert the radiant energy of every line to a analog electric signal • A output device to show the final results

  16. 2.3. Instrumentation 1. Light source 2. Spectrometer 3. Detector 4. Readout

  17. 2.3.1 Light Source

  18. Inductively Coupled Plasma

  19. ICP initial processes

  20. Light Source Progresses

  21. 2.3.2 Spectrometer ⑴Monochromatic Optical-direct Read Spectrometer ⑵Polychromatic Optical-direct Read Spectrometor

  22. 1. Dispersion⑴Prism

  23. (2) Grating

  24. Dispersion Mechanism of Grating

  25. Grating Equation (2.3) For a blazed reflection grating (echelette) (2.4) Where: : blaze angle, nr: number of grooves / mm, : wavelength, m: grating order : incident angle, : diffracted angle,

  26. Angle Dispersion of a Grating (2.5) linear dispersion (2.6) Reciprocal linear dispersion Dr (2.7)

  27. Resolving Power (2.8) Blazing range (2.9)

  28. 2. A Typical Monochromator

  29. Two-dimensional Array Produced by the echelle Mount

  30. 3. Detector ⑴Spectrograph ⑵Photomultiplier Tube ⑶Segmented-array Charge-Coupled Detector(SCD)

  31. ⑴Spectrograph ⑵Photomultiplier Tube

  32. Multiply Phototube

  33. ⑶Segmented-array Charge-Coupled Detector(SCD) Fig 3-16 Scheme of SCD Detector

  34. ICP-AES Instrumentation System

  35. 2.4 Analytical Methods of AES 1. Qualitative Analysis ⑴Standard Iron Spectra Comparison ⑵Indicate Element Spectra Comparison ⑶Determination of Line Wavelength

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