EFFECT OF TENSION ON R-LINES IN RUBY CRYSTALS SHOCKED ALONG CRYSTAL C-AXIS

An experimental method has been developed to measure the wavelength sh ift of R lines in ruby samples subjected to well-defined, large tensil e stresses. Plate impact experiments, conducted at 77 K, were used to produce uniaxial strain tension along the crystal c axis. Longitudinal stresses ranged from 105 kbar in tension to 110 kbar in compression. Both R lines remained sharp and showed a reversible, nonlinear blueshi ft in tension; the R1-R2 splitting increases with increasing tension. The observed data are in excellent agreement with predictions using cr ystal field theory [Sharma and Gupta, Phys. Rev. B 43, 879 (1991)]. Th e present results also permit an examination of the tensile response o f sapphire at these large stresses.