Absorption of an Exciton and Exciton propagation

[Sciencestd]

I read articles talk about the absorption of the exciton in a solvent, such as TIPS Pentracene in toluene. My question is does the absorption spectrum keep the same for aggregate TIPS Pentracene , in case if I want to know for a layer of TIPS Pentracene?!

My second question is: let's say I know absorption spectrum of Exciton, such as TIPS Pentracene, and I excite it with wavelength between two maxima in the absorption spectrum (not necessary that is minimum but a region between two maxima)... does then exciton propagation occurs?

 

[azntoon]

The absorption spectra of a material depends on the environment it is in, so the absorption spectrum of TIPS Pentracene in toluene may be different than that of an aggregate or a layer. Therefore, it is not possible to determine the exact absorption spectrum for a layer of TIPS Pentracene without performing an experiment.When you excite a material with a wavelength between two maxima in the absorption spectrum, the exciton will likely not propagate. This is because the energy of the excitation will be too low for the exciton to move.