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Dive into the research topics where Lucian Baia is active.

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Featured researches published by Lucian Baia.


Journal of Non-crystalline Solids | 2002

Structural investigations of copper doped B2O3–Bi2O3 glasses with high bismuth oxide content

Lucian Baia; Razvan Stefan; W. Kiefer; Jürgen Popp; S. Simon

Raman and infrared spectroscopy have been employed to investigate the 99.5%[xB2O3(1−x)Bi2O3]0.5%CuO glasses with different Bi/B nominal ratios (0.07⩽x⩽0.625) in order to obtain information about the competitive role of B2O3 and Bi2O3 in the formation of the glass network. The glass samples have been prepared by melting at 1100 °C and rapidly cooling at room temperature. In order to relax the structure, to improve the local order and to develop crystalline phases the glass samples were kept at 575 °C for 10 h. The influence of both Bi2O3 and CuO on the vitreous B2O3 network as well as the local order changes around bismuth and boron atoms in as prepared and heat treated samples was studied. Structural modifications occurring in heat treated samples compared to the untreated glasses have been observed.


Journal of Non-crystalline Solids | 2003

Vibrational spectroscopy of highly iron doped B2O3-Bi2O3 glass systems

Lucian Baia; Razvan Stefan; Jürgen Popp; S. Simon; W. Kiefer

Abstract Glass systems of composition 95%[xB2O3(1−x)Bi2O3]5%Fe2O3 with different Bi/B nominal ratios (0.07⩽x⩽0.90) have been investigated by means of Raman and infrared spectroscopy in order to obtain information about the competitive role of B2O3 and Bi2O3 in the formation of the glass network. The glass samples have been prepared by melting at 1100 °C and rapidly cooling at room temperature. The samples have been further kept at 575 °C for 10 h in order to relax the glasses structure as well as to improve the local order and to develop the new formed crystalline phases. The influence of both Bi2O3 and Fe2O3 on the vitreous B2O3 network as well as the local order changes around bismuth and boron atoms in as prepared and heat-treated samples have been studied. Structural modifications occurring in the heat-treated samples compared to the untreated glasses have been pointed out.


Nanotechnology | 2007

Controlling gold nanoparticle assemblies for efficient surface-enhanced Raman scattering and localized surface plasmon resonance sensors

F. Toderas; Monica Baia; Lucian Baia; Simion Astilean

Gold nanoparticle assemblies with different particle densities were immobilized upon functionalized glass substrates and their morphology and optical properties are analysed with TEM and UV?vis absorption spectroscopy. The efficiency of self-assembled gold colloidal nanoparticles as SERS-active substrates at 633?nm excitation line is evaluated by employing p-aminothiophenol. The average enhancements in the range of 105?107 are consistent with signals being dominated by molecules adsorbed at junctions inside nanoparticle assemblies. We employ an annealing treatment to induce changes in the initial morphology of gold assemblies and produce sensitive LSPR substrate. The sensitivity of the as-prepared substrate to transduce changes of the surrounding medium refractive index is further assessed.


Applied Physics Letters | 2006

Surface-enhanced Raman scattering efficiency of truncated tetrahedral Ag nanoparticle arrays mediated by electromagnetic couplings

Monica Baia; Lucian Baia; Simion Astilean; Juergen Popp

Surface-enhanced Raman scattering (SERS) efficiency assessment of truncated tetrahedral Ag nanoparticle arrays with different vertical dimensions prepared by nanosphere lithography provides the experimental evidence of the electromagnetic (EM) coupling sensitivity to the nanoparticle heights. It is demonstrated that the EM couplings between the localized plasmon resonance of each particle and photonic modes of the particles array are solely accountable for the SERS enhancement of the rhodamine 6G molecules adsorbed on these substrates. Similar nanoparticle height dependent SERS enhancement trend is observed for the resonant excitation of the probe molecule.


Journal of Molecular Structure | 2001

Raman and IR spectroscopic studies of manganese doped GeO2–Bi2O3 glasses ☆

Lucian Baia; T. Iliescu; S. Simon; W. Kiefer

Abstract 99.5% [ x GeO 2 (1− x )Bi 2 O 3 ] 0.5% MnO glasses with different Bi/Ge nominal ratios (0.20≤ x ≤0.875) have been investigated by means of Raman and IR spectroscopies. The influence of bismuth atoms on the vitreous GeO 2 network as well as the changes of the local order both around bismuth and germanium atoms are studied. The very low content of MnO introduced in these samples has no structural effect on the bismuth–germanate matrices as far as evidenced by the methods used.


Applied Spectroscopy | 2002

Confocal Micro-Raman Spectroscopy: Theory and Application to a Hybrid Polymer Coating

Lucian Baia; K. Gigant; U. Posset; G. Schottner; W. Kiefer; Jürgen Popp

Confocal micro-Raman spectroscopy has been applied for vibrational investigations on a sol-gel derived hybrid polymer coating. In order to characterize the dimensions of the focus inside the coating, the substrate, and the coating/substrate, a model that considers both the refraction and diffraction effects has been developed. A coating of ∼20.2 μm thickness applied to polycarbonate substrate has been investigated. The spatial distribution of the Raman intensity in the focal volume was studied at different depths within the sample and the Raman response at the corresponding levels has been calculated. The selection in depth of the Raman response, given by the confocal pinhole, was also taken into account. In comparing the prediction of this theoretical model to the empirical results, a good agreement has been observed.


Journal of Materials Science | 2009

Synthesis, structural characterization, and photocatalytic properties of iron-doped TiO2 aerogels

M. Popa; L. Diamandescu; Florin Vasiliu; C. M. Teodorescu; Veronica Cosoveanu; Monica Baia; M. Feder; Lucian Baia; Virginia Danciu

Fe(III)-doped TiO2 aerogels are prepared by acid catalyzed sol–gel method followed by supercritical drying, and then heat treatment. Raman spectra together with X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns of the iron-doped TiO2 aerogel samples revealed the existence of both anatase and brookite crystalline phases. It was found that the brookite phase formation is favored by the increase of the iron content in the dried samples. XRD measurements show that the lattice constant c of anatase phase decreases with the dopant addition, while the value of a remains essentially unchanged. The microstructure of the investigated samples is relatively compact with small mesopores as revealed from transmission electron microscopy (TEM). The most enhanced photocatalytic activity was exhibited by the TiO2 aerogel sample with 1.8 at.% Fe(III) whose apparent rate constant of the salicylic acid photodegradation was found to be of almost six times higher than that of Degussa P25.


Journal of Sol-Gel Science and Technology | 2003

Inorganic-organic cross-linking in UV curable hard coats based upon vinyltriethoxysilane-tetraethoxysilane-polyfunctional acrylate hybrid polymers: A Raman spectroscopic study

K. Gigant; U. Posset; G. Schottner; Lucian Baia; W. Kiefer; Jürgen Popp

Hydrolysis, polycondensation and UV-induced radical polymerization processes in binary and ternary mixtures of vinyltriethoxysilane (VTEOS), tetraethoxysilane (TEOS), and several polyfunctional acrylates as reactive diluents were studied by means of FT-Raman and confocal micro-Raman spectroscopy. The study comprises measurements on sols, gels, xerogels, and thin films applied on top of glass slides and polymeric substrates. Characteristic Raman bands are utilized to gain information about the structural evolution, inorganic network connectivity, and organic cross-linking reactions. Supplementary, 29Si-NMR spectroscopic data are considered and correlated with Raman data. Structure-property correlations based on spectroscopic and mechanical data are outlined and discussed. It is demonstrated that thin hybrid polymer films may be studied in-situ by means of confocal micro-Raman spectroscopy.


Journal of Biomedical Materials Research Part A | 2012

Bioactivity and protein attachment onto bioactive glasses containing silver nanoparticles

Adriana Vulpoi; C. Gruian; E. Vanea; Lucian Baia; S. Simon; Heinz Jürgen Steinhoff; G. Göller; Viorica Simon

There is much interest in silver containing glasses for use in bone replacement owing to the demonstrated antibacterial effect. In this work, 2 and 8 mol % of silver was added during the sol-gel process to the composition of a bioactive glass belonging to CaO-SiO(2 -P(2)O(5) system. The samples were characterized by means of ultraviolet-visible spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques to demonstrate that the silver is embedded into the glass matrix as nanoparticles. Bioactivity test in simulated body fluid proved that the presence of silver in the bioactive glass composition, even in high amount, preserve or even improve the bioactivity of the starting glass, and consequently, leads to the carbonated apatite formation, which is the prerequisite for bioactive materials to bond with living bones. Complementary information proving these findings were delivered by performing X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and XPS measurements. The presence of silver also improves protein binding capability to the bioactive glass surface as demonstrated by cw-electron paramagnetic resonance experiments and XPS measurements.


ChemPhysChem | 2009

Multilayer Structures of Self-Assembled Gold Nanoparticles as a Unique SERS and SEIRA Substrate†

Monica Baia; F. Toderas; Lucian Baia; Dana Maniu; Simion Astilean

Metallic multilayer structures consisting of self-assembled nanoparticles are prepared by successive immersion of a functionalized glass substrate in a gold colloidal suspension, and are characterized by UV/Vis spectroscopy and atomic force microscopy. The ability of the thin film to concomitantly enhance the Raman and IR signals of an adsorbed molecule is evaluated and a detailed analysis of the recorded spectra is provided, which emphasizes the capability of these complementary methods to provide information about the adsorbed species. This unique surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption (SEIRA) substrate could be further used for applications in the elucidation of the structure of a great variety of adsorbed samples.

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Virginia Danciu

Warsaw University of Technology

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Jürgen Popp

Leibniz Institute of Photonic Technology

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W. Kiefer

University of Würzburg

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Zs. Pap

University of Szeged

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Anca Peter

Technical University of Cluj-Napoca

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