UV Absorption in Linear Polyenes


butatdiene orbitals

 



Background:

Click on the graph to display the various bonding and antibonding molecular orbitals and energies. Use Surfaces from the Jmol popup menu to display other molecular orbitals for each polyene.

  • All the molecular orbitals for ethylene(ethene), 1,3-butadiene, 1,3,5-hexatriene, and 1,3,5,7-octatetraene are available.
  • Note the increasing number of nodes as the conjugated chain increases
  • Addition of successive conjugated double bonds progressively narrows the gap between HOMO and LUMO
  • Thus longer wavelength (lower energy) radiation required for the chromophore transition

 

 

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