Observation of stimulated emission from Rhodamine 6G-polymer aggregate adsorbed at foam interfaces

Abstract

This paper reports for the first time the observation of stimulated emissions from the gas-liquid interface between two adjacent bubbles in highly ordered foams containing Rhodamine 6 G and surfactant. Stimulated emissions centred at 595 nm were observed when a monolayer of foam (∼liquid fraction 0.11), placed on a highly reflective surface, was pumped with a 532 nm continuous wave laser directed along ∼45°from the direction perpendicular to the substrate. Additionally, using confocal microscopy and micro-photoluminescence, it was found that the liquid fraction of the foam, the gap between two adjacent bubbles and the incidence angle of the laser are important parameters in guiding the light and promoting stimulated emissions at the interface. The adsorption of the polymer and dye increased the local concentration at the narrowest gaps between pairs of bubbles, which led to the formation of hemispherical micelles-dye agglomerates. The presence of the micelles aggregation caused random scattering induced stimulated emission. These results could have a significant impact on a number of applications, such as photocatalytic conversion at bubble interfaces, where TiO 2 can scatter light and hence reaction rates may be increased.

Effect of Oleic Acid Coating of Iron Oxide Nanoparticles on Properties of Magnetic Polyamide-6 Nanocomposite

“…Polymer nanocomposites (PNCs) that can respond to external stimuli, namely electric, optical or magnetic, are proving promising for various applications, such as drug delivery, information storage, electromagnetic interference shielding, magnetic resonance imaging, environmental remediation, microscale manufacturing and self-healing. [1][2][3][4][5] Nanoparticles (NPs) naturally exhibit a strong tendency to agglomerate, as this minimizes the energy interactions linked with their high surface area to volume ratio. Moreover, increasing NP loading reduces the inter-particle distances, allowing the formation of the agglomerates due to short range van der Waals or hydrogen bonds, as observed in particle aggregation at the air-liquid interface in bubbles.…”

“…Moreover, increasing NP loading reduces the inter-particle distances, allowing the formation of the agglomerates due to short range van der Waals or hydrogen bonds, as observed in particle aggregation at the air-liquid interface in bubbles. 3,4 The presence of NP agglomerates in the polymer matrix causes an uneven material heating in response to the applied stimulus, as the region with agglomerated particles will quickly absorb much of the stimulus energy and will melt the surrounding polymer excessively or undergo pyrolysis. 5 Therefore, mechanical and chemical dispersion techniques can be employed to achieve uniform heating of the polymer in nanocomposites.…”

Mechanoresponsive Hard Elastic Materials Based on Semicrystalline Polymers: From Preparation to Applied Properties

“…The fluorescent character of these aggregates is directly proved by the corresponding excitation spectra. Aggregation of xanthene dyes in the electronic ground state is known to be a well-studied phenomenon for the concentrated solutions of dyes and for dense and mesostructured dye-doped films. − As follows from Figure , all samples show a single emission band with a maximum in the 580–600 nm region (580, 587, and 595 nm for samples 1, 2, and 3, respectively) upon excitation in the 420–530 nm region (with the excitation maxima at 548, 555, and 565 nm, respectively). Therefore, on increasing the number of loading cycles, the excitation and emission bands are gradually shifted to the red-wavelength spectral region.…”

“…The above polar groups can play a decisive role in the formation of nonfluorescent sandwich H-dimers or fluorescent head-to-tail J-dimers, which are widely discussed in the exciton theory. Aggregation of Rh6G molecules in the T-shaped J-type dimers may be provided by the hydrogen-bonding interaction of boundary hydrogen atoms from one molecule with delocalized π-electrons from the other molecule . In principle, similar conformations may also be characteristic of higher-order fluorescent aggregates.…”

Dispersion and Interaction of Charged Fluorescent Dyes in Protein‐Polymer Surfactant‐based Non‐Aqueous Liquid

“…Also, selective interaction of fluorescent probes with certain region of a protein has enormous utility in site‐specific binding related photo‐physical studies. Rhodamine 6G (Rh6G) and fluorescein (FL) are well known positively and negatively charged hydrophilic dyes, respectively, with their structures shown in Figure b and c …”