Cuprate superconductivity: some spectroscopic, structural, and chemical aspects

HTS results obtained by steady-state and time-dependent spectroscopy of spontaneous Raman scattering and by the quantum-beat technique are analyzed. The copper—oxygen chain structure is analyzed by invoking the charge-density-wave concept and the donor—acceptor interaction between chemical-bond partners. Stimulated Raman and hyper-Raman scattering and the low-frequency acoustic spectroscopy of spontaneous Raman scattering are discussed in terms of their prospects for HTS experiments.