Intensity behaviour in the near ultraviolet spectra of chloro and fluoro derivatives of the benzene chromophore

The Interaction Vector Model (IVM) is used to understand the behaviour of t he intensity of the secondary transition of chloro derivatives of the benze ne chromophore, extending the work to some fluoro derivatives. These latter molecules show a surprising result: the ortho and meta interaction vectors for fluoro disubstituted molecules point in directions opposed to what has been observed in the whole preceding works.