Effect of alkanes on the disorder-to-order transition of naphthalenes on Al2O3

Resonance Energy Transfer from Alkylbenzene Substrates to Naphthalene and Biphenyl Overlayers on Al2O3

“…A seed crystal in the ampoule containing the melt was lowered through a sharp temperature gradient, and the result was a boule or a single-crystal ingot. , In this paper, comparable mixed crystals were made by vapor deposition of a bilayer containing the host/guest molecules onto a cryogenically cooled chemically inert surface of Al 2 O 3 and, subsequently, subjecting the bilayer to temperature-programmed desorption (TPD). At deposition temperatures, guest molecules such as naphthalene are known to exhibit fluorescence that is spectrally broad and red-shifted relative to the monomer. − Previous studies of solutions with high concentrations of aromatic molecules have identified the origin of this fluorescence to the formation of transient excimers. − During the TPD, the two different molecules can be made to mix by ensuring that the adlayer of the molecule with the higher desorption temperature is deposited on top. Hence, the molecule deposited adjacent to the surface will percolate through the adlayer above and by choosing molecules with appropriate energy states, energy transfer was observed between the molecules. − In this study, heteroepitaxy is demonstrated as the alkylbenzene substrate ordered and caused the overlayer of naphthalene or biphenyl to crystalize that resulted in enhanced fluorescence from defect sites.…”

“…At deposition temperatures, guest molecules such as naphthalene are known to exhibit fluorescence that is spectrally broad and red-shifted relative to the monomer. − Previous studies of solutions with high concentrations of aromatic molecules have identified the origin of this fluorescence to the formation of transient excimers. − During the TPD, the two different molecules can be made to mix by ensuring that the adlayer of the molecule with the higher desorption temperature is deposited on top. Hence, the molecule deposited adjacent to the surface will percolate through the adlayer above and by choosing molecules with appropriate energy states, energy transfer was observed between the molecules. − In this study, heteroepitaxy is demonstrated as the alkylbenzene substrate ordered and caused the overlayer of naphthalene or biphenyl to crystalize that resulted in enhanced fluorescence from defect sites. Near the desorption temperature, resonance energy transfer (RET) occurred as the substrate passed through the upper layer of naphthalene fluorophores.…”