Optical properties of an electron bound to a double well potential in a dielectric

Abstract

The absorption and emission properties of F2+ center in KCl (2 adjacent anion vacancies which bind 1 electron) were investigated between 0.6 and 5 eV by using an optically aligned center system. Energy positions, level degeneracies, polarization behavior and oscillator strengths of 8 absorption transitions were found in close agreement to the calculated states of the H2+ molecular ion corrected for a single dielectric constant and the proper separation between the 2 effective positive charges. Excitation of the lowest 2póu state at 1.38 ì leads with temperature independent quantum efficiency to a Stokes shifted emission at 1.67 ì almost in mirror symmetry with the zero phonon line at 1.5260 ì. Excitation of all higher absorption transitions (2pðu, etc.) at liquid helium temperature (LHeT) produces a visible luminescence at 600 nm. At higher temperature a thermally activated process (activation energy ÄE = 0.063 eV) transfers the excitation energy to the lowest excited state 2póu quenching the 600-nm luminescence and producing the IR emission.