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SPECTROSCOPY PowerPoint Presentation

               
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happyindia By : happyindia

On : May 21, 2016

In : Education & Training

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SPECTROSCOPY
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  • Slide 1 - SPECTROSCOPY
  • Slide 2 - 4.1 Spectral Lines 4.2 Atoms and Radiation The Hydrogen Atom 4.3 The Formation of Spectral Lines The Photoelectric Effect 4.4 Molecules 4.5 Spectral-Line Analysis Information from Spectral Lines Units of Chapter 4
  • Slide 3 - Spectroscope: Splits light into component colors 4.1 Spectral Lines
  • Slide 4 - Emission lines: Single frequencies emitted by particular atoms 4.1 Spectral Lines
  • Slide 5 - Emission spectrum can be used to identify elements 4.1 Spectral Lines
  • Slide 6 - Absorption spectrum: If a continuous spectrum passes through a cool gas, atoms of the gas will absorb the same frequencies they emit 4.1 Spectral Lines
  • Slide 7 - An absorption spectrum can also be used to identify elements. These are the emission and absorption spectra of sodium: 4.1 Spectral Lines
  • Slide 8 - Kirchhoff’s Laws: Luminous solid, liquid, or dense gas produces continuous spectrum Low-density hot gas produces emission spectrum Continuous spectrum incident on cool, thin gas produces absorption spectrum 4.1 Spectral Lines
  • Slide 9 - Kirchhoff’s laws illustrated: 4.1 Spectral Lines
  • Slide 10 - Existence of spectral lines required new model of atom, so that only certain amounts of energy could be emitted or absorbed Bohr model had certain allowed orbits for electron 4.2 Atoms and Radiation
  • Slide 11 - Emission energies correspond to energy differences between allowed levels Modern model has electron “cloud” rather than orbit 4.2 Atoms and Radiation
  • Slide 12 - Energy levels of the hydrogen atom, showing two series of emission lines: 4.2 Atoms and Radiation The energies of the electrons in each orbit are given by: The emission lines correspond to the energy differences
  • Slide 13 - The photoelectric effect: When light shines on metal, electrons can be emitted Frequency must be higher than minimum, characteristic of material Increased frequency—more energetic electrons Increased intensity—more electrons, same energy 4.2 Atoms and Radiation
  • Slide 14 - Photoelectric effect can only be understood if light behaves like particles 4.2 Atoms and Radiation
  • Slide 15 - Light particles each have energy E: Here, h is Planck’s constant: 4.2 Atoms and Radiation
  • Slide 16 - Absorption can boost an electron to the second (or higher) excited state Two ways to decay: To ground state Cascade one orbital at a time 4.3 The Formation of Spectral Lines
  • Slide 17 - (a) Direct decay (b) Cascade 4.3 The Formation of Spectral Lines
  • Slide 18 - Absorption spectrum: Created when atoms absorb photons of right energy for excitation 4.3 The Formation of Spectral Lines Multielectron atoms: Much more complicated spectra, many more possible states Ionization changes energy levels
  • Slide 19 - Emission lines can be used to identify atoms 4.3 The Formation of Spectral Lines
  • Slide 20 - Molecules can vibrate and rotate, besides having energy levels Electron transitions produce visible and ultraviolet lines Vibrational transitions produce infrared lines Rotational transitions produce radio-wave lines 4.4 Molecules
  • Slide 21 - Molecular spectra are much more complex than atomic spectra, even for hydrogen: (a) Molecular hydrogen (b) Atomic hydrogen 4.4 Molecules
  • Slide 22 - Information that can be gleaned from spectral lines: Chemical composition Temperature Radial velocity 4.5 Spectral-Line Analysis
  • Slide 23 - Line broadening can be due to a variety of causes 4.5 Spectral-Line Analysis
  • Slide 24 - 4.5 Spectral-Line Analysis
  • Slide 25 - 4.5 Spectral-Line Analysis The Doppler shift may cause thermal broadening of spectral lines
  • Slide 26 - 4.5 Spectral-Line Analysis Rotation will also cause broadening of spectral lines through the Doppler effect
  • Slide 27 - Spectroscope splits light beam into component frequencies Continuous spectrum is emitted by solid, liquid, and dense gas Hot gas has characteristic emission spectrum Continuous spectrum incident on cool, thin gas gives characteristic absorption spectrum Summary of Chapter 4
  • Slide 28 - Spectra can be explained using atomic models, with electrons occupying specific orbitals Emission and absorption lines result from transitions between orbitals Molecules can also emit and absorb radiation when making transitions between vibrational or rotational states Summary of Chapter 4 (cont.)
  • Slide 29 - THANK YOU

Description : SPECTROSCOPY ppt presentation a brief description about science topic SPECTROSCOPY.

Tags : Spectroscopy | | Solar System Exploration | types of spectroscopy | spectroscopy lab