Transient absorption results are presented on two types of GaSe nanoparticle aggregates. The results indicate that both types of aggregates exhibit larger emission oscillator strengths than the corresponding monomers, that is, superradiance. One type of GaSe nanoparticle is synthesized by conventional methods, and the other is synthesized at room temperature from very small GaSe particle nuclei. The latter type of particles form very strongly interacting aggregates, presumably because they have fewer edge-binding ligands. In both cases, the extent of superradiance is inferred from the stimulated emission band in the transient absorption spectrum. Oscillator strength ratios (n-aggregate/n monomers) are 1.5 and 1.8-2.0 for the conventional and cold-synthesized aggregates, respectively. These ratios can be quantitatively understood in terms of an electrostatic coupling model and random inhomogeneous broadening in the aggregates.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films