Luminescence of Excitonic Molecules Distributed around k=0 in CuCl

Abstract

Excitonic molecule state in CuCl has been resonantly excited by the combination of two circularly polarized laser beams of slightly different energies and of the opposite propagation vectors. The secondary emissions associated with the excitonic molecule state of a quite small momentum have been investigated by changing the spectral width of the incident laser light. With the increase of the band width of excitation laser, the luminescence becomes dominant and the Raman component is suppressed. An emission line at 3.1869 eV is assigned to the luminescence due to the decomposition of excitonic molecules, distributed in a region of ±0.022k₀ around 0.050k₀, into a pair of polaritons, where k₀ is the wave vector of the photon of 3.1861 eV. The relaxation of the excitonic molecule system really generated at the small momentum region has been discussed.