  New electronic Raman and I.R. spectroscopy results from optimally and
overdoped high temperature superconducting (HTSC) cuprate systems are
interpreted in terms of the negative-U, boson-fermion crossover model.
Distinction is made between those features which follow the condensate gap,
2Delta(p), and those that are set by the local-pair binding energy, cursive
U(p). The critical role of doping level psubc = 0.185 is highlighted in
conjunction with the matter of developing quasiparticle incoherence, making
connection here with recent transport and related results. E//c IR results in
magnetic fields parallel and perpendicular to c prove particularly
illuminating. The general scheme developed continues to embrace all
experimental data very satisfactorily.
