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We have investigated the deformation mechanism of ruby in a microscopic area using a femtosecond laser having a pulse width, wavelength, and repetition rate of 238 fs, 780 nm, and 1 kHz, respectively. Transmission electron microscope observation revealed that a specific oblique pattern originating from cracks having a width of approximately 10 nm formed at the focal point. The peak shift of ruby fluorescence indicated the existence of a residual stress of 0.11 GPa at the irradiated area. Considering the pattern and magnitude of the residual stress at the focal point, we suggest that the crack propagated along the rhombohedral planes and the planes by laser irradiation. [ABSTRACT FROM AUTHOR]

Abstract: We have made the XANES measurements at the Cr–K edge on natural Burma ruby single crystals (corundum) and its two irradiated samples with fluence 1×1012 Fe3+ and 1×1013 Fe3+ions/cm2. XANES measurements show progressive increase in the intensity of pre-edge features (1s→3d), while intensity of 1s→4p transition Cr reduces with Fe fluence. Crystal field-splitting energy is found to be a 2.2eV and unchanged in irradiated samples. [Copyright &y& Elsevier]

Photoluminescence spectra measured for pristine ruby and its two irradiated samples with Fe 3+ ion show R 1 , R 2 , N lines and a broad band. Decrease in intensities of these features is observed with irradiation of Fe 3+ ion in ruby. Progressive structural changes and modifications on surface of irradiated rubies with Fe 3+ ion have been observed by atomic force microscopy. Decrease in intensities is discussed in terms of pair formation. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution of mechanical stresses in Al2O3:Cr single crystal irradiated with (1÷3) MeV/amu Kr, Xe and Bi ions has been studied by using laser confocal scanning microscopy technique. The stress level as a function of the ion penetration depth has been evaluated from depth-resolved photostimulated R-line luminescence spectra exploiting the piezospectroscopic method. As it was found, the stress field generated by swift heavy ion irradiation is composed of stresses with maximal magnitude comparable with the ultimate stress limit of ruby crystals. Experimental data are discussed in the framework of a model considering the Cr3+ atoms as individual piezosensors. [Copyright &y& Elsevier]