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Spectroscopy
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Spectroscopy

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  • 1. Astronomy Thomas Cooper
  • 2. The spectroscopic technique used to assess the  concentration or amount of a given species, such as the elements that make up a star.  The instrument that performs such measurements is a spectrometer or spectrograph.  Most large telescopes have spectrometers, which are used either to measure the chemical composition and physical properties of astronomical objects or to measure their velocities from the Doppler shift of their spectral lines.
  • 3. Telescope – to capture radiation  Dispersion Device – to spread the radiation  out into a spectrum  Detector – to record the results
  • 4. Most spectroscopic methods are differentiated as  either atomic or molecular based on whether or not they apply to atoms or molecules. Along with that distinction, they can be classified on the nature of their interaction:  Absorption spectroscopy uses the range of the electromagnetic spectra in which a substance absorbs.  Emission spectroscopy uses the range of electromagnetic spectra in which a substance radiates (emits).  Scattering spectroscopy measures the amount of light that a substance scatters at certain wavelengths, incident angles, and polarization angles.
  • 5. A luminous solid, liquid or  dense gas emits at all wavelengths and produces a continuous spectrum.  A low-density, hot gas emits light whose spectrum consist of a series of bright emission lines that represent it’s chemical composition. (Emission Lines).  A cool, thin gas absorbs certain wavelengths from a continuous spectrum, leaving dark absorption lines. (Absorption Lines)
  • 6. Spectral Emissions of a Supernova
  • 7. (1787-1826)  Physicists  Catalogued over 600  absorption lines  Now know as Fraunhofer lines
  • 8. Lines that represent wavelengths of light that were removed (absorbed) by gasses present in the outer layers of the sun.
  • 9. Ground State – normal energy state Exited State – contains more than the normal amount of energy Ionized State – electron has exceeded the maximum energy state
  • 10. N81, an emission nebula An interstellar cloud made mostly of hydrogen gas excited by absorbing radiation emitted by extremely hot stars.
  • 11. Change in Energy State  Change in Vibrational State  Change in Rotational State 
  • 12. Absorption of additional energy can boost the electron into even higher orbitals within the atom. As it cascades down to the ground state, it emits photons, each with a different energy and wavelength.