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UV Visible Spectroscopy

  1. Name - Jadhav Avinash J Roll no - 2K13E11 SavitriBai Phule Pune University 1
  2. Contents  Electromagnetic spectrum Definition Diagram Light absorption Electronic excitation Application 2
  3. WHAT IS SPECTROSCOPY? Atoms and molecules interact with electromagnetic radiation (EMR) in a wide variety of ways. Atoms and molecules may absorb and/or emit EMR Absorption of EMR stimulates different types of motion in atoms and/or molecules. 3
  4. 4 •The patterns of absorption (wavelengths absorbed and to what extent) and/or emission (wavelengths emitted and their respective intensities) are called ‘spectra’. •The field of spectroscopy is concerned with the interpretation of spectra in terms of atomic and molecular structure (and environment).
  6. UV-Visible Instrumentation 6
  7. UV-Visible Instrumentation Light source Deuterium and hydrogen lamps Sample containers Cuvettes  Plastic  Glass  Quartz 7
  8. BEER-LAMBERT LAW For a light absorbing medium, the light intensity falls exponentially with sample depth. For a light absorbing medium, the light intensity falls exponentially with increasing sample concentration. 100% x I I T I I T o t o t       == 8 Io It l cuvette Sample depth
  9. BEER-LAMBERT LAW clA It I A λε= = 0 log 9
  10. BEER-LAMBERT LAW limitations • Polychromatic Light • Equilibrium shift • Solvent • pH 10
  11. Electronic transitions Electronic transitions Molecular Orbital 11
  12. Application Ultraviolet radiation stimulates molecular vibrations and electronic transitions. Absorption spectroscopy from 160 nm to 780 nm Measurement absorption or transmittance Identification of inorganic and organic species 12
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