Triplet emission of atomic ytterbium isolated in a xenon matrix
Nadezhda N. Kleshchina, Inna S. Kalinina, Ricardo Lewis Lambo +3 more
The electronic transitions of ytterbium atoms in a solid Xe matrix grown at 4.8 K are investigated. Absorption bands are detected in the regions of the gas-phase 6s2 1S0 → 4f135d6s2 and 6s2 1S0 → 6s6p 1P1 transitions. Both bands indicate that Yb atoms occupy multiple trapping sites, of which three are identified. Emission induced by the 6s2 1S0 → 6s6p 1P1 excitation is found to be concentrated entirely in the region of the 6s6p 3PJ → 6s2 1S0 decay, whereas the singlet emission is completely quenched. Multiple emission peaks are observed and the effects of annealing and prolonged irradiation on their amplitudes are found to be significant and are interpreted as a consequence of Yb population transfer from one type of site to another. Modeling of the ground-state site structure and stability predicts three Yb/Xe occupation types, substitutional (ss), tetravacancy (tv) and hexavacancy (hv), in order of decreasing stability. Their tentative associations with observed absorption and emission features are discussed. Time correlated single photon spectroscopy is used to determine the lifetimes of the individual emission bands. They are found to be different from each other with indications of a mixture of short- and long- lived 6s6p 3PJ fine-structure components and demonstrate distinct temperature dependencies. A dramatic decrease in the lifetime of the emission peak tentatively assigned to the most stable site with temperature is explained by a competition between the radiative and non-radiative decay paths of the 6s6p 3P1 state. The mechanism of the latter can be attributed to electron–phonon coupling as confirmed by a model of the temperature-dependence of the lifetime.
Low Temperature Physics•Jul 1, 2019•4 citations