Photon echoes and site-selective raman scattering of samarium-vacancy dipoles

Abstract

Electronic Raman scattering of Sm²⁺ in KCl is performed under resonant interconfigurational excitation around 500 nm. The position of the charge-compensating cation vacancy with respect to the substitutional Sm²⁺ ion is derived from both the Stark splitting of the J-levels and the polarization properties of the scattered light. The influence of the different site symmetries on the optical linewidth is investigated with photon echoes, stimulated from an accumulated grating, which is built up under intraconfigurational excitation between the ⁷ F ₀ and the ⁵ D ₁ terms of the 4f ⁶5 _s ²5 _p ⁶ ground state configuration. The echo decay time is about 10 ps and does not change sizably when tuning the excitation frequency over the inhomogeneous distribution. This shows that for zero-phonon line excitation, the Sm²⁺ sites are not very different. The temperature dependence of the echo is described by vertical relaxation to the bottleneck under multi-phonon emission.