Optical Properties of Low-Dimensional Molecular Crystals and LB Films
A general theory for calculating spectroscopic properties of low-dimensional molecular crystals is developed on the basis of the cluster approach. Electronic correlations and the coupling of electrons to intramolecular vibrations are explicitly taken into account. The relative role of different model parameters is investigated and both effects are found to be equally important. This result predicts a possibility to modify physical properties via the choice of constituents, stoichiometry, or external conditions (temperature, pressure, photoexcitation, etc.). The theory explains well the experimental visible and infrared spectra and proves that the optical response in molecular charge-transfer crystals has a local nature. Charge-transfer salts prepared in the form of Langmuir-Blodgett (LB) films are also discussed. The cluster approach analysis of the experimental absorption spectra of LB films is shown to provide information about molecular organization and can offer a way to modify the optical response as required by specific practical applications.
KeywordsInfrared Spectrum Spectroscopic Property Molecular Crystal Equilibrium Charge Intramolecular Vibration
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