6 May 1996 Generation of nonequilibrium paraexcitons due to orthoparaexciton conversion
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Proceedings Volume 2796, ICONO '95: Fundamentals of Laser-Matter Interaction; (1996) https://doi.org/10.1117/12.239757
Event: International Conference on Coherent and Nonlinear Optics, 1995, St. Petersburg, Russian Federation
The renormalization of the energetic spectrum of paraexcitons in the presence of the Bose- Einstein condensate of orthoexcitons, or at least of their saturation, is studied. Due to the conversion of a pair of orthoexcitons into a pair of paraexcitons an absolute instability in the energy spectrum of paraexcitons appears. The paraexcitons that appeared can be downscattered by optical phonon (Gamma) 5-(88 cm-1) in a state above the bottom of the paraexciton band. This could be the reason for the observed peculiarities in the paraexciton luminescence band. On this basis a new explanation of the extra peak appearance in the luminescence spectrum of the uniaxially stressed Cu2O crystal is suggested. It has the same origin as the bump of the luminescence band in unstrained crystal. The spectral positions of the extra peak and of the bump differ due to the diminution of the ortho-para splitting in uniaxially stressed crystals. The difference of their widths is due to different densities of the condensed orthoexcitons in stressed and unstrained crystals.
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A. I. Bobrysheva, S. A. Moskalenko, M. I. Shmiglyuk, S. S. Russu, "Generation of nonequilibrium paraexcitons due to orthoparaexciton conversion", Proc. SPIE 2796, ICONO '95: Fundamentals of Laser-Matter Interaction, (6 May 1996); doi: 10.1117/12.239757; https://doi.org/10.1117/12.239757

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