The lowest excita1on is from the highest occupied

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Unformatted text preview: tion is not bad considering the model simplicity 13 Par1cle in a box. General argument The energy of a particle in a box is given by 2π 2 2 n 2 2 mL We therefore expect that the wavelength of excitation will be longer (lower energy) when the box size increases. This ia useful hint for design of dyes and holds experimentally: ethene 170nm, hexatriene, 265nm 14 Besides par1cle in a box we also learned about a par1cle in a ring. Can we find an example for excita1on of a par1cle in a ring? Benzene molecule is approximated by a ring with radius of about 1.5Å 15 Energy levels for benzene as a ring n=4 n=3 There are six electrons in the π system of benzene. The lowest excita1on is from the highest occupied orbital to the lowest unoccupied one. n=2 n=1 n=0 16 π spectroscopy of benzene 2 2 En =...
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