7B5—Energy Transfer in Ruby

The transfer of energy from single chromium ions to closely coupled pairs of chromium ions in ruby has been investigated. Ruby samples whose concentrations ranged from 0.003 to 1.0 percent Cr2O3 were prepared and in each crystal the intensity of single-ion fluorescence and of pair fluorescence was accurately measured. Radiative decay measurements were also made in an attempt to unravel the dynamics of the transfer process. The transfer from single ions to pairs is shown to occur nonradiatively, and its efficiency is enhanced by a fast energy transfer between individual single ions. The possibility is explored that an electric quadrupole-quadrupole interaction is responsible for this transfer process.