Thermal variations of iodine nanostructures inside the channels of AlPO4-5 zeolite single crystals

The structural changes of ordered hexagonal arrays of iodine nanostructures enclosed inside one-dimensional channels of aluminophosphate zeolites are studied. These isolated nanochains undergo structural transformations between linked chains and separated molecules, as shown by tracing the temperature variations of their distinctive Raman features when these nanostructures are heated thermally to the transition temperature of similar to 70 degrees C. The reversibility of this transition is improved by replacing the conventional thermal heating with localized heating using a focused laser beam, which reduced the diffusion along the channels. In addition, the optically identified transition is consistently confirmed by thermal characterization using differential scanning calorimetric and thermal gravimetric analyses.