RESUMEN
We propose a method of spatial modulation of inhomogeneous broadening of a quantum-well excitonic resonance based on local generation of defects produced by a focused ion beam. The method is applied to fabrication of excitonic diffraction grating in a single quantum-well InGaAs/GaAs structure by irradiating the sample with a beam of 35-keV He+ ions of exposure doses <1012 cm-2. The spectrum of resonant diffraction on such a structure is narrower than that of reflectivity and decreases much faster with increasing temperature. A proposed model of formation of the diffractive response based on the single scattering approximation well describes the results of the spectral and temperature measurements.
RESUMEN
The characteristics of luminescence, excited by long wavelength radiation, in various solid systems (ionic crystals, activated by rare earth elements; semiconducting crystals with absorbed layers of sensitizer dye; green leaves of plants) have been investigated. It was found that in all cases studied the emission arises as a result of cooperative processes, owing to interactions of two or more excited states. The role of cooperative excitation in the phenomenon of sensitization of various photochemical and photophysical processes is pointed out.