Phonon-assisted energy transfer within dimers in Pr 3+: CaF 2

Abstract

Time-resolved, site-selective laser spectroscopy has been used to study the nonresonant energy transfer between inequivalent Pr 3+ ions in a well-defined dimer site in Pr 3+:CaF 2. The mechanism of the nonresonant energy transfer was determined from the temperature dependence of the energy transfer rate to be a one-phonon direct process at low temperatures and a combination of the one-phonon process and resonant, two-phonon processes (Orbach processes) at temperatures above 10 K. Application of a magnetic field had no discernible effect on the energy transfer rate because no significant Zeeman splittings occurred.