Bahrs, S., S. Reich, A. Zwick, A. R. Goni, W. Bacsa, G. Nieva, and C. Thomsen. "Raman spectroscopy with UV excitation on untwinned single crystals of YBa2Cu3O7-delta." PHYSICA STATUS SOLIDI B-BASIC RESEARCH 241, no. 12 (2004): R63–R66.
Abstract: Recent reflectance anisotropy studies on the material showed a photobleaching effect in the in-plane components of the dielectric function around 2.2 and 4.1 eV . We present Raman spectra of oxygen deficient YBa2Cu3O7-delta detwinned single crystals taken with laser excitation of 3.7 eV, close to the UV feature in the dielectric function, in search for a signal from the defect-induced Raman modes. While two groups of defect-induced mode at 230 cm(-1) and 600 cm(-1) behave very similar at the 2.2 eV resonance, we find clear differences for UV excitation. A peak at 600 cm(-1) is identified as a copper-oxygen-chain related, defect-induced modes by its Raman selection rules. While this mode is enhanced beyond the strength of the Raman-allowed modes, the group at 230 cm(-1) is absent. Low temperature experiments showed no change of the peak height under illumination, though the peaks are known to photobleach in the visible. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.