抄録
Highly sensitive momentum-space spectroscopy, named two-photon polarization spectroscopy (TPPS), is presented in the Z3 exciton resonant region of CuCl. This spectroscopy is based on the induced optical anisotropy associated with the formation of Γ1 excitonic molecules (EM’s). By this method the following facts are confirmed: the upper branch polaritons (UBP’s) and the lower branch polaritons (LBP’s) coexist in the wide energy range above the longitudinal exciton energy; the conversion of UBP into LBP occurs in the reflection at the sample boundary; the EM relaxation depends on the wave number in the large wave number region. From the quantitative analysis of the spectra, it has been found that the damping of the Z3 exciton depends strongly on its energy in the L–T gap region. The prospects of the ABC problem are also discussed.
