Synergistic photoabsorption: Range effectiveness of the cooperative and distributive mechanisms

A recently discovered two-photon absorption process can produce novel features in spectra obtained with intense broadband radiation. Two mechanisms termed cooperative and distributive contribute to the effect, which involves synergistic photoabsorption by molecular pairs. In the former mechanism, each molecule of the pair absorbs a single photon; in the latter, two photons are absorbed by one of the molecules. In contrast to earlier suggestions, it is here shown that the distributive mechanism is far more significant over large intermolecular distances.