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Raman spectroscopy, IR absorption: Effect of high pressure on the optical properties of materials

RAMAN Experimental Setup
The optical properties of a wide range of materials (semiconductors, fullerenes, nanotubes, garnets etc) are studied using Raman, IR absorption and photoluminescence spectroscopies as well as theoretical calculations (RIM, FP LMTO).
These techniques are used for material characterization (identification of polytype, crystallinity ratio, stress, etc) as well as for the study of fundamental physical phenomena like, lattice dynamics, electronic properties, electron – phonon interaction, study of immediate neighboring, etc. The application of external parameters e.g. temperature and pressure affects the optical properties providing thus information on the physical phenomena themselves and, on the other site, allows the investigation of regions of structural stability of materials and the study of pressure induced phase transitions. These studies are important from the point of view of the basic research (understanding of physical interactions) and for the understanding of the behaviour of materials under extreme conditions.
Activities:
1.Study of the pressure – induced phase transitions and optical properties of semiconductors (III-V, II-VI), fullerenes and related compounds.
2.Study of the pressure – induced phase transitions using Raman spectroscopy of Scheelite compounds (ABO4, with A=Ca, Sr, Ba etc and B=W, Mo).
3.Study of III-V nitrides (AlN, Gan, InN and their alloys) using Raman spectroscopy: effect of ion implantation and doping as well as of the stresses induced during the epitaxial growth.
4.Study of the Raman spectra and the lattice dynamics of Al and Ga garnets, RE3Al5O12, RE3Ga5O12 (RE=rare earth).
Equipment
1.RAMALOG 5 Raman spectrometer with a triple-monochromator that covers the wavelength range 12000 – 28000 cm-1 (8500-3500Å) (1978) fully automated and PC controlled.
2.Two Ar+ lasers of Spectra Physics 2W (1978 & 2008).
3. One Kr laser of Lexel 1.5W (1993).
4.One cryostat accompanied by the diffusion pump of Cryogenic that works down to 20K (1982).

CALENDAR

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