Two‐Stage Excitation of the Phosphorescence of Ruby
Z. L. Morgenshtern, Vladimir B. Neustruev
Abstract A long‐time phosphorescence of ruby is found under intense optical excitation in the spectral region of the R‐lines. From the initial brightness decay, as a function of the intensity and wavelength of the exciting light, it is suggested that the phosphorescence has a recombination character. The long‐wavelength limit of excitation corresponds to about 2 eV. These results indicate a complex character for the phosphorescence excitation (two‐photon or two‐step). To differentiate between these two possibilities experiments are performed using two excitation pulses with various time delays between them. These experiments show that two‐step excitation of electrons into the conduction band of ruby takes place over 2E levels of the Cr ions. From the results, and absorption data of ruby and corundum, a band scheme is proposed which explains the long‐wavelength limit of phosphorescence excitation in terms of indirect transitions.
physica status solidi (b)•Jan 1, 1966•9 citations