Localization and interaction of indirect excitons in GaAs coupled quantum wells

We introduced an elevated trap technique and exploited it for lowering the effective temperature of indirect excitons. We observed narrow photoluminescence lines which correspond to the emission of individual states of indirect excitons in a disorder potential. We studied the effect of exciton-exciton interaction on the localized and delocalized exciton states and found that the homogeneous line broadening increases with density and dominates the linewidth at high densities

Transport of indirect excitons in ZnO quantum wells

We report on spatially- and time-resolved emission measurements and observation of transport of indirect excitons in ZnO/MgZnO wide single quantum wells

Exciton front propagation in photoexcited GaAs quantum wells

We report on the study of spatiotemporal self-organization of carriers in photoexcited GaAs quantum wells. Propagating interfaces between electron-rich and hole-rich regions are seen as expanding and collapsing exciton rings in exciton emission patterns. The interfaces preserve their integrity during expansion, remaining as sharp as in the steady state, which indicates that the dynamics is controlled by carrier transport. The front propagation velocity is measured and compared to theoretical model. The measurements of expanding and collapsing exciton rings afford a contactless method for probing the electron and hole transport.United States. Army Research OfficeNational Science Foundatio

Exciton Gas Transport through Nanoconstrictions.

An indirect exciton is a bound state of an electron and a hole in spatially separated layers. Two-dimensional indirect excitons can be created optically in heterostructures containing double quantum wells or atomically thin semiconductors. We study theoretically the transmission of such bosonic quasiparticles through nanoconstrictions. We show that the quantum transport phenomena, for example, conductance quantization, single-slit diffraction, two-slit interference, and the Talbot effect, are experimentally realizable in systems of indirect excitons. We discuss similarities and differences between these phenomena and their counterparts in electronic devices

Nonlinear optical spectroscopy of indirect excitons in coupled quantum wells

International audienceIndirect excitons in coupled quantum wells are long-living quasiparticles, explored in the studies of collective quantum states. We demonstrate that, despite the extremely low oscillator strength, their spin and population dynamics can by addressed by time-resolved pump-probe spectroscopy. Our experiments make it possible to unravel and compare spin dynamics of direct excitons, indirect excitons, and residual free electrons in coupled quantum wells. Measured spin relaxation time of indirect excitons exceeds not only one of direct excitons but also one of free electrons by two orders of magnitude

Gadolinium Orthovanadate GdVO4:Eu3+ Nanoparticles Ameliorate Carrageenan-Induced Intestinal Inflammation

Gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) have been shown to scavenge reactive oxygen species (ROS), making them a promising therapeutic agent in inflammation. This study aims to assess the effects of VNPs administered orally on E407a-induced inflammation. Materials and Methods: Fragments of the small intestine of 8 rats treated orally with a carrageenan-containing food additive E407a at a dose of 140 mg / kg of weight during 2 weeks, 8 animals orally exposed to both E407a and VNPs at a dose of 20 μg / kg of weight during the same period of time, and 8 control rats were stained routinely and immunostained for CD3 and CD68 with the subsequent immunohistochemical scoring. Moreover, analysis of viability and cell death modes of granulocytes was performed by flow cytometry using Annexin V and 7-aminoactinomycin D (7-AAD). Results: Oral exposure to the food additive E407a resulted in the development of enteritis associated with altered small intestinal morphology, infiltration of the lamina propria with macrophages and T-lymphocytes, and activation of peripheral blood granulocyte apoptosis. VNPs administered against the background of E407a-induced slight intestinal inflammation improved small intestinal morphology, decreased infiltration rate of the immune cells mentioned above without affecting the intensity of granulocyte apoptosis. Conclusion: Oral administration of VNPs ameliorates E407a-induced enteritis