1,720,989 research outputs found
Spontaneous and field-assisted transition in K0.984Li0.016TaO3: study of the polar pattern by birefringence and second-harmonic generation
No full textThe polar transition in Li-doped and Nb-doped KTaO3: comparative analysis from hard-phonon Raman spectra
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Forbidden Raman scattering in pure and doped lithium niobate
No full textWe studied the effects of photorefractive activity on Raman scattering in pure, Mg-doped and Fe-doped single crystals of lithium niobate. We found that in Fe-doped lithium Niobate the build-up of light-induced anisotropic scattering strongly affects the relative intensities of Raman lines in specific experimental geometries
Origin of the blue fluorescence in Dominican amber
No full textWe report on optical absorption, fluorescence, and time-resolved fluorescence measurements in Dominican ambers. The "blue" variety reveals an intense fluorescence emission in the visible wavelength region, between 430 and 530 nm, with spectral features typical of aromatic hydrocarbons. On the contrary, the "red" and "yellow" varieties have a much weaker and featureless emission. The data for blue amber, including fluorescence lifetime, allow the identification of perylene as the compound responsible for its distinctive showy fluorescence
Structural and optical defects in LiNbO3 crystals induced by femtosecond laser irradiation
No full textMicrostructural modifications, induced by femtosecond laser irradiation on Lithium Niobate (LN) crystals were investigated by means of optical microscopy and micro-Raman spectroscopy. Commercial z-cut congruent LN substrates were irradiated with focused ultra-short laser pulses at 810 nm. At the focus region either structural changes or material removal were observed by varying the irradiation conditions. The mapping of Raman spectrum revealed the insurgence of Raman modes, which are forbidden in the used scattering geometry. This phenomenon increases gradually by approaching the ablation region
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