Transport of Electronic Excitation Energy in Dye-Loaded Zeolite L

Zeolite L is an aluminosilicate with one-dimensional channels, having an opening diameter of 7.1 Å. This allows the incorporation of different, electronically non-interacting dye molecules to build an artificial photonic antenna system. The conditions within the channels are such that the dye molecules cannot glide past each other. Hence, a consecutive incorporation leads to crystals with different compartments, where the density of one kind of dye is dominant. The photophysical processes taking place on such dye-loaded zeolite L antenna systems can be studied either on single micrometer or submicrometer sized crystals, on crystals dispersed in a solvent, orcoated as thin layers on a support. The energy transfer process that occurs is of the Förster-type and its transfer rate can be tuned, e.g. by first incorporating the acceptor dyes, in a second step consecutively incorporating different amounts of spacer molecules and then in a third step adding the donor dyes. By selectively exciting the donor, energy transfer to the unexcited acceptor as a function of the amount of spacer molecules can be observed. To make a quantitative analysis, one has to take into consideration the situation at the phase boundaries of the particular compartments. This has been done by modeling the distribution of the dye molecules and empty sites within a zeolite crystal by means of a Monte Carlo simulation.