Inhomogeneous electron paramagnetic resonance line broadening in ruby

Abstract

The angular variations of the electron paramagnetic resonance linewidths of the ΔM = 1 transitions at 35 GHz have been studied in rubies grown by the vapour phase, Verneuil and Czochralski processes and having chromium concentrations in the range 0.015 to 0.20 at.%. Using a strain and mosaic model, parameters characterizing the strain at the Cr³⁺ sites and the axial misorientation have been derived by a least-squares analysis. The spread in zero-field splitting is typically about 5×10^-4 cm^-1, giving Δ(2D)/2D similar, equals 10^-3. The values of the strain components e_xx, e_zz and e_xz lie in the range 10^-4 to 2×10^-2 and appear to be growth dependent.