Strong chiroptical effects in surface second harmonic generation obtained for molecules exhibiting excitonic coupling chirality

We measured nonlinear optical activity in second harmonic generation (SHG) by reflection on a thin film of chiral molecules. We selected the structure of our molecules in order to obtain very large chiroptical effects. We indeed measured an angle of rotation of the second harmonic polarization as large as 66° for an acridine substituted Trِger base. This is in good agreement with our theoretical expectations for such an excitonic coupling chirality.