3C3 - Geometrical model and experimental verification of two-photon absorption in organic dye solutions

Two-photon absorption in solutions of organic dyes has been quantitatively measured in a wide range of wavelengths, extinction coefficients, and concentrations. The measurements are shown to be in good agreement with the simple assumption that the probability of double hits of photons on the area extended by the π-electron cloud of a molecule determines the rate of two-photon absorption.