We report on a systematic study of optical properties of (Ga,Mn)As epilayers spanning the wide range of accessible substitutional MnGa dopings. The growth and post-growth annealing procedures were optimized for each nominal Mn doping in order to obtain films which are as close as possible to uniform uncompensated (Ga,Mn)As mixed crystals. We observe a broad maximum in the midinfrared absorption spectra whose position exhibits a prevailing blue-shift for increasing Mn-doping. In the visible range, a peak in the magnetic circular dichroism blue shifts with increasing Mndoping. These observed trends confirm that disorder-broadened valence band states provide a better one-particle representation for the electronic structure of high-doped (Ga,Mn)As with metallic conduction than an energy spectrum assuming the Fermi level pinned in a narrow impurity band.PACS numbers: 74.20. Mn, 74.25.Nf, 74.72.Bk, 74.76.Bz The discovery of ferromagnetism in (Ga,Mn)As above 100 K [1] opened an attractive prospect for exploring the physics of magnetic phenomena in doped semiconductors and for developing advanced concepts for spintronics. Assessment of a wide range of magnetic and transport properties of the material [2][3][4] showed that in ferromagnetic (Ga,Mn)As with Mn dopings x > 1%, disorderbroadened and shifted host Bloch bands represent a useful one-particle basis for describing this mixed-crystal degenerate semiconductor. The common kinetic-exchange model implementation of this valence band theory and the more microscopic tight-binding Anderson model or ab-initio density functional theory can all be shown [5] to be mutually consistent on the level of atomic and orbital resolved band structure. The main utility of valence band theories have been in providing a qualitative and often semi-quantitative description of phenomena originating from the exchange split and spin-orbit coupled electronic structure and in assisting the development of prototype spintronic devices [4]. Other basic physical properties of (Ga,Mn)As, namely those reflecting the vicinity of the metal-insulator transition and localization and electronelectron interaction effects, remain to be fully understood and require to go beyond the commonly employed perturbative or disorder averaged Bloch-band theories.In the insulator non-magnetic regime (x 1%), the system is readily described by localized Fermi level states residing inside a narrow impurity band separated from the valence band by an energy gap of magnitude close to the isolated Mn Ga impurity binding energy. Recently, a debate has been stirred by proposals, based in particular on optical spectroscopy measurements [6], that the narrow impurity band persists in high-doped (Ga,Mn)As with metallic conduction. Several phenomenological variants of the impurity band model have been proposed for the high-doped regime [6][7][8][9][10] which are mutually inconsistent from the perspective of the assumed atomic orbital nature of the impurity band states [5]. Further theoretical inconsistencies arise when recreating ...

In this paper, it is demonstrated how Raman spectroscopy can be used to detect different carotenoids as possible biomarkers in various groups of microorganisms. The question which arose from previous studies concerns the level of unambiguity of discriminating carotenoids using common Raman microspectrometers. A series of laboratory-grown microorganisms of different taxonomic affiliation was investigated, such as halophilic heterotrophic bacteria, cyanobacteria, the anoxygenic phototrophs, the non-halophilic heterotrophs as well as eukaryotes (Ochrophyta, Rhodophyta and Chlorophyta). The data presented show that Raman spectroscopy is a suitable tool to assess the presence of carotenoids of these organisms in cultures. Comparison is made with the high-performance liquid chromatography approach of analysing pigments in extracts. Direct measurements on cultures provide fast and reliable identification of the pigments. Some of the carotenoids studied are proposed as tracers for halophiles, in contrast with others which can be considered as biomarkers of other genera. The limits of application of Raman spectroscopy are discussed for a few cases where the current Raman spectroscopic approach does not allow discriminating structurally very similar carotenoids. The database reported can be used for applications in geobiology and exobiology for the detection of pigment signals in natural settings.

FT Raman spectroscopy and micro-Raman spectroscopy with lasers of three different wavelengths (1064 nm, 785 nm and 532 nm) were used for analysis of reference samples of natural clay pigments including white clay minerals (kaolinite, illite, montmorillonite), green earths (glauconite and celadonite) and red earths (natural mixtures of white clay minerals with hematite). In addition, eight micro-samples obtained from historical paintings containing clay pigments in ground and colour layers have been examined. Powder X-ray diffraction and micro-diffraction were used as supplementary methods. It was found that laser operating at 1064 nm provided the best quality Raman spectra for distinguishing different white clay minerals, but the spectra of green and red earths were affected by strong fluorescence caused by the presence of iron. Green earth minerals could be easily distinguished by 532 or 785 nm excitation lasers, even in small concentrations in the paint layers. On the other hand, when anatase (TiO 2 ) or iron oxides (such as hematite) were present as admixtures (both are quite common, particularly in red earths), the collection of characteristic spectra of clay minerals which form the main component of the layer was hindered or even prevented. Another complicating factor was the fluorescence produced by organic binders when analysing the micro-samples of artworks. In those cases, it is always necessary to use powder X-ray micro-diffraction to avoid misleading interpretations of the pigment's composition.

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The non-centrosymmetric polar tetragonal (P4 1 ) barium antimony tartrate trihydrate, Ba[Sb 2 ((+)C 4 H 2 O 6 ) 2 ]·3H 2 O, was found to be an attractive novel semi-organic crystal manifesting numerous χ (2) -and χ (3) -nonlinear optical interactions. In particular, with picosecond single-and dualwavelength pumping SHG and THG via cascaded parametric four-wave processes were observed. High-order Stokes and anti-Stokes lasing related to two SRS-promoting vibration modes of the crystal, with ω SRS1 575 cm −1 and ω SRS2 2940 cm −1 , takes place. Basing on a spontaneous Raman investigation an assignment of the two SRS-active vibration modes is discussed.

Two methods of analysis of organic components of colour layers of art works have been tested: IR microspectroscopy of indigo, Cu-phthalocyanine, and Prussian blue, and MALDI-TOF-MS of proteinaceous binders and a protein-containing red dye. The IR spectra distortion common for smooth outer surfaces and polished cross sections of colour layer of art works is suppressed by reflectance measurement of microtome slices. The detection limit of the three blue pigments examined is approximately 0.3 wt% in reference colour layers in linseed oil binder with calcite as extender and lead white as a drying agent. The sensitivity has been sufficient to identify Prussian blue in repaints on a Gothic painting. MALDI-TOF-MS has been used to identify proteinaceous binders in two historical paintings, namely isinglass (fish glue) and rabbit glue. MALDI-TOF-MS has also been proposed for identification of an insect red dye, cochineal carmine, according to its specific protein component. The enzymatic cleavage with trypsin before MALDI-TOF-MS seems to be a very gentle and specific way of dissolution of the colour layers highly polymerised due to very long aging of old, e.g. medieval, samples.

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