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Handbook of Solvents - George Wypych - ChemTech - Ventech!

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11.1 Theoretical treatment <strong>of</strong> solvent effects 643<br />

Scheme 9 Scheme 10<br />

Scheme 11<br />

Scheme 12<br />

Scheme 13 Scheme 14<br />

Scheme 15 Scheme 16<br />

Scheme 17<br />

The solvent-induced broadening <strong>of</strong> the spectral lines and bands arises primarily from<br />

the variation <strong>of</strong> the local environment <strong>of</strong> the chromophoric solute molecule in the condensed<br />

medium caused by the thermal motion <strong>of</strong> the surrounding solvent molecules. At any<br />

given instant <strong>of</strong> time, there is a distribution <strong>of</strong> differently solvated solute molecules, each <strong>of</strong><br />

which has characteristic transition energy to the excited state. The respective distribution <strong>of</strong><br />

the transition energies leads to the broadening <strong>of</strong> the spectral band. It has to be kept in mind,<br />

however, that the broadening <strong>of</strong> spectral lines and bands can be also originated from adjoin-

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