Mirjana Comor | The Vinca Institute of Nuclear Sciences (original) (raw)
Papers by Mirjana Comor
The Journal of Physical Chemistry, 1990
... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovi... more ... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovit, Mirjana I. Comor, Vesna Vasiir, and Olga I. Mitic* "Boris KidriE" Institute, Vifica. ... Chem. 1988, 92, 4706. (8) Kamat. PV; Dimitrijevic, NM; Fessenden, RW J . Phys. Chem. 1987, 91, 396. ...
Journal of Colloid and Interface Science, 2006
In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (A... more In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (ACE) inhibitor, with cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated. The effect of cationic micelles on the spectroscopic and acid-base properties of QUIN was studied at pH 8. The binding of QUIN anion to CTAB micelles implied a shift in drug acidity constant (pK(a)(water)-pK(a)(micelle)=1.39) proving the great affinity of negatively charged QUIN ion for the positively charged CTAB micelle surface. The strong dependence of the partition coefficient K(x) on QUIN concentration, obtained by using pseudo-phase model, is consistent with an adsorption-like phenomenon. From the dependence of differential absorbance at lambda=272 nm on CTAB concentration, by using mathematical model that treats the solubilization of QUIN anion as its binding to specific sites in the micelles (Langmuir adsorption isotherm), the binding constant K(b)=(2.3+/-0.4)x10(3) mol(-1)dm(3) was obtained. QUIN-CTAB binding constant was also calculated from micellar liquid chromatography (MLC) and this method was found to be not accurate enough for its determination.
Journal of Hazardous Materials, 2010
The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the ph... more The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light (lambda > or = 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO(2) (rutile/anatase) and of the most frequently used TiO(2) Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.
2009 International Semiconductor Conference, 2009
In this paper we present the optimization procedure for the application of gold nanoparticles as ... more In this paper we present the optimization procedure for the application of gold nanoparticles as a system for the detection of oligonucleotides. The gold nanoparticles have been conjugated to a pair of 5'alkanethiol-modified 20 base oligonucleotides, designed to align in a tail-to-head manner. Upon hybridization with the complementary target, the plasmon region of the spectra registers a large red-shift, thus forming a reliable colorimetric system for the detection of oligonucleotides.
Journal of Physical Chemistry B, 2006
Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) wer... more Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) were used for the synthesis of anatase TiO 2 particles, while rutile TiO 2 particles were synthesized in aqueous media by acidic hydrolysis of titanium(IV) chloride. The X-ray diffraction measurements proved the exclusive presence of either the anatase or the rutile phase in prepared samples. The photoluminescence of both kinds of particles (anatase and rutile) with several well-resolved peaks extending in the visible spectral region was observed, and the quantum yield at room temperature was found to be 0.25%. Photon energy up-conversion from colloidal anatase and rutile TiO 2 particles was observed at low excitation intensities. The energy of up-converted photoluminescence spans the range of emission of normal photoluminescence. The explanation of photon energy up-conversion involves mid-gap energy levels originating from oxygen vacancies.
Journal of Materials Science Letters, 1998
Semiconductor particles that exhibit size-dependent optical and electronic properties are termed ... more Semiconductor particles that exhibit size-dependent optical and electronic properties are termed quantized particles, or quantum dots (QDs) . Recently, several papers have reported quantization effects in nano-crystalline particles, consisting of layered semiconductor materials such as iodides (HgI 2 [2± 5], PbI 2 [6±8], BiI 3 [3, 6, 7]) and sul®des (Bi 2 S 3 [9], Sb 2 S 3 [9], MoS 2 [10], WS 2 [10]). A major feature of the results for layered semiconductor QDs is the presence of well-resolved peaks in the absorption spectra, in addition to the large blue shift of the fundamental absorption that is characteristic of quantized semiconductor particles [2±6]. In the previous works, the colloids were prepared in three different ways: (a) by reaction of appropriate metal salts with iodide or sul®de ions [2±4, 6, 9]; (b) by taking advantage of different solubility of monomeric HgI 2 species in alcohol and water ; and (c) by simple dissolution of crystalline powder in acetronitrile .
Journal of Physical Chemistry C, 2011
Here we report results of systematic investigation of heterogeneity and disorder in Ti{sub 1-x}Fe... more Here we report results of systematic investigation of heterogeneity and disorder in Ti{sub 1-x}Fe{sub y}O{sub 2-d} nanorod rutile-based flowerlike aggregates. It was found that Ti{sub 1-x}Fe{sub y}O{sub 2-d} aggregates are composed of two crystalline phases: rutile as a dominant and anatase as a minor phase. Flowerlike aggregates were found to grow from an isometric core ca. 5-10 nm in diameter
The Journal of Physical Chemistry, 1990
... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovi... more ... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovit, Mirjana I. Comor, Vesna Vasiir, and Olga I. Mitic* "Boris KidriE" Institute, Vifica. ... Chem. 1988, 92, 4706. (8) Kamat. PV; Dimitrijevic, NM; Fessenden, RW J . Phys. Chem. 1987, 91, 396. ...
Applied Catalysis B-environmental, 2004
The kinetics and possible mechanism of the photocatalytic degradation of herbicide mecoprop, in U... more The kinetics and possible mechanism of the photocatalytic degradation of herbicide mecoprop, in UV illuminated aqueous colloids of synthesized nanosized TiO2 were investigated. The rate of degradation was studied by 1H NMR, UV spectrometry, as well ...
Journal of Hazardous Materials, 2010
The aim of this work was to study the efficiency of Fe-and N-doped titania suspensions in the pho... more The aim of this work was to study the efficiency of Fe-and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ( ≥ 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO 2 (rutile/anatase) and of the most frequently used TiO 2 Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.
Original organic capping TOPO/TOP groups of CdSe and CdSe/ZnS quantum dots (QDs), from mother sol... more Original organic capping TOPO/TOP groups of CdSe and CdSe/ZnS quantum dots (QDs), from mother solution were replaced with 2_mercaptoethanol, which was chosen as model compound, in order to achieve water solubility. Obtained water dispersions of CdSe and CdSe/ZnS QDs were characterized by UV/VIS absorption and luminescence techniques. Luminescence measurements revealed that bare cores are very sensitive to surface capping, transfer into water diminished emission intensity. Core/shell, CdSe/ZnS, QDs are much more resistant to changes of the capping and solvent, and significant part of emission intensity was preserved in water.
Chemical Physics Letters, 1999
new method for the preparation of 25 A AgBr quantum dots has been developed. The room-temperature... more new method for the preparation of 25 A AgBr quantum dots has been developed. The room-temperature emission of size-restricted AgBr crystallites was observed. The emission spectrum of 25 A AgBr quantum dots is characterized by the presence of two bands centered at 340 and 420 nm. A room-temperature luminescence quantum yield of ; 0.4% was determined. Several reasons for the enhancement of the emission of the normally nonemissive indirect band gap of the AgBr material are discussed. q 1999 Elsevier Science B.V. All rights reserved.
Optical Materials, 2008
Nonaqueous reaction between titanium(IV) chloride and benzyl alcohol was used for the synthesis o... more Nonaqueous reaction between titanium(IV) chloride and benzyl alcohol was used for the synthesis of highly crystalline TiO 2 nanorods. The X-ray diffraction measurements proved the exclusive presence of the anatase phase. The photoluminescence of anatase TiO 2 nanorods with several well-resolved emission bands was observed, and quantum yield at room temperature was found to be 2.5 · 10 À3 . Photon energy up-conversion from colloidal TiO 2 nanorods was observed at low excitation intensities. The energy of the up-converted photoluminescence spans the range of energies displayed by the normal photoluminescence emission of the TiO 2 nanorods. The explanation for the photon energy up-conversion involves mid-gap energy levels.
Journal of Colloid and Interface Science, 2006
In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (A... more In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (ACE) inhibitor, with cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated. The effect of cationic micelles on the spectroscopic and acid-base properties of QUIN was studied at pH 8. The binding of QUIN anion to CTAB micelles implied a shift in drug acidity constant (pK(a)(water)-pK(a)(micelle)=1.39) proving the great affinity of negatively charged QUIN ion for the positively charged CTAB micelle surface. The strong dependence of the partition coefficient K(x) on QUIN concentration, obtained by using pseudo-phase model, is consistent with an adsorption-like phenomenon. From the dependence of differential absorbance at lambda=272 nm on CTAB concentration, by using mathematical model that treats the solubilization of QUIN anion as its binding to specific sites in the micelles (Langmuir adsorption isotherm), the binding constant K(b)=(2.3+/-0.4)x10(3) mol(-1)dm(3) was obtained. QUIN-CTAB binding constant was also calculated from micellar liquid chromatography (MLC) and this method was found to be not accurate enough for its determination.
Nanoscale Research Letters, 2009
Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipita... more Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5-7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2 into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence.
Materials Chemistry and Physics, 2006
Polymer nanocomposites (NSPANI/AuNP/GR) based on nanostructured polyaniline, gold nanoparticles (... more Polymer nanocomposites (NSPANI/AuNP/GR) based on nanostructured polyaniline, gold nanoparticles (AuNP) and graphene nanosheets (GR) have been synthesized using in situ polymerization. A series of nanocomposites have been synthesized by varying the concentration of GR and chloroauric acid to optimize the formulation with respect to the electrochemical activities. Out of these series of NSPANI/AuNP/GR nanocomposites, it has been found that only one particular nanocomposite has the best electrochemical properties, as analyzed by cyclic voltammetry (CV) and differential pulse voltammetry and conductivity. The best nanocomposite has been characterized by Fourier transform infrared Raman spectroscopy, UV-vis spectroscopy, X-ray diffraction studies, transmission electron microscopy, scanning electron microscopy and atomic force microscopy. The CV of the best nanocomposites show the well-defined reversible redox peaks characteristic of polyaniline, confirming that the polymer maintains its electro activity in the nanocomposites. Another nanocomposite has been prepared with identical composition (as found with the best nanocomposite) by mixing of presynthesized nanostructured polyaniline with chloroauric acid and graphene dispersion in order to predict the mechanism of in situ polymerization. It is inferred that the nanocomposite prepared by blending technique loses its property within 48 h indicating phase separation whereas the nanocomposite prepared by in situ technique is highly stable.
Journal of Alloys and Compounds, 2010
We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5nm. These materia... more We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5nm. These materials have been studied using photoluminescence spectroscopy with various excitation energies in the temperature range from 1.8 to 300K. We registered surface and defect states as well as two Mn2+ energy levels that correspond to Mn2+ ions in two different crystal environments. In addition, the resonant behavior of one Mn state excited by 514.5nm wavelength of laser light has been clearly observed in obtained spectra. We proposed the scheme of energy levels and transitions that explain obtained experimental results.
European Polymer Journal, 2002
Nowadays, polymer composites are widely used in many fields of technology. Among them a significa... more Nowadays, polymer composites are widely used in many fields of technology. Among them a significant roles play polymers containing semiconductor particles, especially for the manufacturing of electronic devices . Therefore, it is important to understand the effects of these fillers on the properties of composites. The properties of composites mostly depend on size and shape of filler particles, their concentration as well as the type of interaction with polymer matrix.
Journal of Physics-condensed Matter, 2004
Cd1-xMnxS quantum dots (QDs) with diameter d \le 4.5 nm and with manganese concentrations from x ... more Cd1-xMnxS quantum dots (QDs) with diameter d \le 4.5 nm and with manganese concentrations from x = 0.001 to 0.15 have been prepared using aqueous solution precipitation. Absorption and fluorescence spectra at room temperature have been recorded. No monotonic variation of the band gap energy with increasing manganese concentration is observed. The electron paramagnetic resonance (EPR) measurements were performed on a 9.5 GHz spectrometer in the temperature range 20 290 K. Two structures in the EPR spectra are observed for all the manganese concentrations: a hyperfine structure and a broad EPR line. The hyperfine structure is described by allowed and forbidden hyperfine transitions of the Mn2+ ion central sextet with hyperfine splitting constant |A| = 9.6 mT and with axial-field splitting parameter D ranging from 11.1 to 13.5 mT. The hyperfine structure is attributed to the isolated Mn2+ ions at or near the surface of the nanocrystals. The width of the broad resonance and its temperature independence suggest that the wide line originates from the noncentral manganese transitions broadened by crystal-field effects, as in some disordered materials.
Journal of Composite Materials, 2012
A Stojanovic, Milena Marinovic-Cincovic, Miodrag Mitric and Mirjana I Comor films poly(vinylalcoh... more A Stojanovic, Milena Marinovic-Cincovic, Miodrag Mitric and Mirjana I Comor films poly(vinylalcohol) composite − Optical, structural and thermal characterization of gold nanoparticles Abstract
The Journal of Physical Chemistry, 1990
... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovi... more ... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovit, Mirjana I. Comor, Vesna Vasiir, and Olga I. Mitic* "Boris KidriE" Institute, Vifica. ... Chem. 1988, 92, 4706. (8) Kamat. PV; Dimitrijevic, NM; Fessenden, RW J . Phys. Chem. 1987, 91, 396. ...
Journal of Colloid and Interface Science, 2006
In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (A... more In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (ACE) inhibitor, with cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated. The effect of cationic micelles on the spectroscopic and acid-base properties of QUIN was studied at pH 8. The binding of QUIN anion to CTAB micelles implied a shift in drug acidity constant (pK(a)(water)-pK(a)(micelle)=1.39) proving the great affinity of negatively charged QUIN ion for the positively charged CTAB micelle surface. The strong dependence of the partition coefficient K(x) on QUIN concentration, obtained by using pseudo-phase model, is consistent with an adsorption-like phenomenon. From the dependence of differential absorbance at lambda=272 nm on CTAB concentration, by using mathematical model that treats the solubilization of QUIN anion as its binding to specific sites in the micelles (Langmuir adsorption isotherm), the binding constant K(b)=(2.3+/-0.4)x10(3) mol(-1)dm(3) was obtained. QUIN-CTAB binding constant was also calculated from micellar liquid chromatography (MLC) and this method was found to be not accurate enough for its determination.
Journal of Hazardous Materials, 2010
The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the ph... more The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light (lambda > or = 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO(2) (rutile/anatase) and of the most frequently used TiO(2) Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.
2009 International Semiconductor Conference, 2009
In this paper we present the optimization procedure for the application of gold nanoparticles as ... more In this paper we present the optimization procedure for the application of gold nanoparticles as a system for the detection of oligonucleotides. The gold nanoparticles have been conjugated to a pair of 5'alkanethiol-modified 20 base oligonucleotides, designed to align in a tail-to-head manner. Upon hybridization with the complementary target, the plasmon region of the spectra registers a large red-shift, thus forming a reliable colorimetric system for the detection of oligonucleotides.
Journal of Physical Chemistry B, 2006
Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) wer... more Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) were used for the synthesis of anatase TiO 2 particles, while rutile TiO 2 particles were synthesized in aqueous media by acidic hydrolysis of titanium(IV) chloride. The X-ray diffraction measurements proved the exclusive presence of either the anatase or the rutile phase in prepared samples. The photoluminescence of both kinds of particles (anatase and rutile) with several well-resolved peaks extending in the visible spectral region was observed, and the quantum yield at room temperature was found to be 0.25%. Photon energy up-conversion from colloidal anatase and rutile TiO 2 particles was observed at low excitation intensities. The energy of up-converted photoluminescence spans the range of emission of normal photoluminescence. The explanation of photon energy up-conversion involves mid-gap energy levels originating from oxygen vacancies.
Journal of Materials Science Letters, 1998
Semiconductor particles that exhibit size-dependent optical and electronic properties are termed ... more Semiconductor particles that exhibit size-dependent optical and electronic properties are termed quantized particles, or quantum dots (QDs) . Recently, several papers have reported quantization effects in nano-crystalline particles, consisting of layered semiconductor materials such as iodides (HgI 2 [2± 5], PbI 2 [6±8], BiI 3 [3, 6, 7]) and sul®des (Bi 2 S 3 [9], Sb 2 S 3 [9], MoS 2 [10], WS 2 [10]). A major feature of the results for layered semiconductor QDs is the presence of well-resolved peaks in the absorption spectra, in addition to the large blue shift of the fundamental absorption that is characteristic of quantized semiconductor particles [2±6]. In the previous works, the colloids were prepared in three different ways: (a) by reaction of appropriate metal salts with iodide or sul®de ions [2±4, 6, 9]; (b) by taking advantage of different solubility of monomeric HgI 2 species in alcohol and water ; and (c) by simple dissolution of crystalline powder in acetronitrile .
Journal of Physical Chemistry C, 2011
Here we report results of systematic investigation of heterogeneity and disorder in Ti{sub 1-x}Fe... more Here we report results of systematic investigation of heterogeneity and disorder in Ti{sub 1-x}Fe{sub y}O{sub 2-d} nanorod rutile-based flowerlike aggregates. It was found that Ti{sub 1-x}Fe{sub y}O{sub 2-d} aggregates are composed of two crystalline phases: rutile as a dominant and anatase as a minor phase. Flowerlike aggregates were found to grow from an isometric core ca. 5-10 nm in diameter
The Journal of Physical Chemistry, 1990
... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovi... more ... Transient Bleaching of Small PBS Colloids. Influence of Surface Properties Milica T. Nenadovit, Mirjana I. Comor, Vesna Vasiir, and Olga I. Mitic* "Boris KidriE" Institute, Vifica. ... Chem. 1988, 92, 4706. (8) Kamat. PV; Dimitrijevic, NM; Fessenden, RW J . Phys. Chem. 1987, 91, 396. ...
Applied Catalysis B-environmental, 2004
The kinetics and possible mechanism of the photocatalytic degradation of herbicide mecoprop, in U... more The kinetics and possible mechanism of the photocatalytic degradation of herbicide mecoprop, in UV illuminated aqueous colloids of synthesized nanosized TiO2 were investigated. The rate of degradation was studied by 1H NMR, UV spectrometry, as well ...
Journal of Hazardous Materials, 2010
The aim of this work was to study the efficiency of Fe-and N-doped titania suspensions in the pho... more The aim of this work was to study the efficiency of Fe-and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ( ≥ 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO 2 (rutile/anatase) and of the most frequently used TiO 2 Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.
Original organic capping TOPO/TOP groups of CdSe and CdSe/ZnS quantum dots (QDs), from mother sol... more Original organic capping TOPO/TOP groups of CdSe and CdSe/ZnS quantum dots (QDs), from mother solution were replaced with 2_mercaptoethanol, which was chosen as model compound, in order to achieve water solubility. Obtained water dispersions of CdSe and CdSe/ZnS QDs were characterized by UV/VIS absorption and luminescence techniques. Luminescence measurements revealed that bare cores are very sensitive to surface capping, transfer into water diminished emission intensity. Core/shell, CdSe/ZnS, QDs are much more resistant to changes of the capping and solvent, and significant part of emission intensity was preserved in water.
Chemical Physics Letters, 1999
new method for the preparation of 25 A AgBr quantum dots has been developed. The room-temperature... more new method for the preparation of 25 A AgBr quantum dots has been developed. The room-temperature emission of size-restricted AgBr crystallites was observed. The emission spectrum of 25 A AgBr quantum dots is characterized by the presence of two bands centered at 340 and 420 nm. A room-temperature luminescence quantum yield of ; 0.4% was determined. Several reasons for the enhancement of the emission of the normally nonemissive indirect band gap of the AgBr material are discussed. q 1999 Elsevier Science B.V. All rights reserved.
Optical Materials, 2008
Nonaqueous reaction between titanium(IV) chloride and benzyl alcohol was used for the synthesis o... more Nonaqueous reaction between titanium(IV) chloride and benzyl alcohol was used for the synthesis of highly crystalline TiO 2 nanorods. The X-ray diffraction measurements proved the exclusive presence of the anatase phase. The photoluminescence of anatase TiO 2 nanorods with several well-resolved emission bands was observed, and quantum yield at room temperature was found to be 2.5 · 10 À3 . Photon energy up-conversion from colloidal TiO 2 nanorods was observed at low excitation intensities. The energy of the up-converted photoluminescence spans the range of energies displayed by the normal photoluminescence emission of the TiO 2 nanorods. The explanation for the photon energy up-conversion involves mid-gap energy levels.
Journal of Colloid and Interface Science, 2006
In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (A... more In this study, the interaction of the anion of quinapril (QUIN), angiotensin converting enzyme (ACE) inhibitor, with cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated. The effect of cationic micelles on the spectroscopic and acid-base properties of QUIN was studied at pH 8. The binding of QUIN anion to CTAB micelles implied a shift in drug acidity constant (pK(a)(water)-pK(a)(micelle)=1.39) proving the great affinity of negatively charged QUIN ion for the positively charged CTAB micelle surface. The strong dependence of the partition coefficient K(x) on QUIN concentration, obtained by using pseudo-phase model, is consistent with an adsorption-like phenomenon. From the dependence of differential absorbance at lambda=272 nm on CTAB concentration, by using mathematical model that treats the solubilization of QUIN anion as its binding to specific sites in the micelles (Langmuir adsorption isotherm), the binding constant K(b)=(2.3+/-0.4)x10(3) mol(-1)dm(3) was obtained. QUIN-CTAB binding constant was also calculated from micellar liquid chromatography (MLC) and this method was found to be not accurate enough for its determination.
Nanoscale Research Letters, 2009
Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipita... more Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5-7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2 into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence.
Materials Chemistry and Physics, 2006
Polymer nanocomposites (NSPANI/AuNP/GR) based on nanostructured polyaniline, gold nanoparticles (... more Polymer nanocomposites (NSPANI/AuNP/GR) based on nanostructured polyaniline, gold nanoparticles (AuNP) and graphene nanosheets (GR) have been synthesized using in situ polymerization. A series of nanocomposites have been synthesized by varying the concentration of GR and chloroauric acid to optimize the formulation with respect to the electrochemical activities. Out of these series of NSPANI/AuNP/GR nanocomposites, it has been found that only one particular nanocomposite has the best electrochemical properties, as analyzed by cyclic voltammetry (CV) and differential pulse voltammetry and conductivity. The best nanocomposite has been characterized by Fourier transform infrared Raman spectroscopy, UV-vis spectroscopy, X-ray diffraction studies, transmission electron microscopy, scanning electron microscopy and atomic force microscopy. The CV of the best nanocomposites show the well-defined reversible redox peaks characteristic of polyaniline, confirming that the polymer maintains its electro activity in the nanocomposites. Another nanocomposite has been prepared with identical composition (as found with the best nanocomposite) by mixing of presynthesized nanostructured polyaniline with chloroauric acid and graphene dispersion in order to predict the mechanism of in situ polymerization. It is inferred that the nanocomposite prepared by blending technique loses its property within 48 h indicating phase separation whereas the nanocomposite prepared by in situ technique is highly stable.
Journal of Alloys and Compounds, 2010
We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5nm. These materia... more We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5nm. These materials have been studied using photoluminescence spectroscopy with various excitation energies in the temperature range from 1.8 to 300K. We registered surface and defect states as well as two Mn2+ energy levels that correspond to Mn2+ ions in two different crystal environments. In addition, the resonant behavior of one Mn state excited by 514.5nm wavelength of laser light has been clearly observed in obtained spectra. We proposed the scheme of energy levels and transitions that explain obtained experimental results.
European Polymer Journal, 2002
Nowadays, polymer composites are widely used in many fields of technology. Among them a significa... more Nowadays, polymer composites are widely used in many fields of technology. Among them a significant roles play polymers containing semiconductor particles, especially for the manufacturing of electronic devices . Therefore, it is important to understand the effects of these fillers on the properties of composites. The properties of composites mostly depend on size and shape of filler particles, their concentration as well as the type of interaction with polymer matrix.
Journal of Physics-condensed Matter, 2004
Cd1-xMnxS quantum dots (QDs) with diameter d \le 4.5 nm and with manganese concentrations from x ... more Cd1-xMnxS quantum dots (QDs) with diameter d \le 4.5 nm and with manganese concentrations from x = 0.001 to 0.15 have been prepared using aqueous solution precipitation. Absorption and fluorescence spectra at room temperature have been recorded. No monotonic variation of the band gap energy with increasing manganese concentration is observed. The electron paramagnetic resonance (EPR) measurements were performed on a 9.5 GHz spectrometer in the temperature range 20 290 K. Two structures in the EPR spectra are observed for all the manganese concentrations: a hyperfine structure and a broad EPR line. The hyperfine structure is described by allowed and forbidden hyperfine transitions of the Mn2+ ion central sextet with hyperfine splitting constant |A| = 9.6 mT and with axial-field splitting parameter D ranging from 11.1 to 13.5 mT. The hyperfine structure is attributed to the isolated Mn2+ ions at or near the surface of the nanocrystals. The width of the broad resonance and its temperature independence suggest that the wide line originates from the noncentral manganese transitions broadened by crystal-field effects, as in some disordered materials.
Journal of Composite Materials, 2012
A Stojanovic, Milena Marinovic-Cincovic, Miodrag Mitric and Mirjana I Comor films poly(vinylalcoh... more A Stojanovic, Milena Marinovic-Cincovic, Miodrag Mitric and Mirjana I Comor films poly(vinylalcohol) composite − Optical, structural and thermal characterization of gold nanoparticles Abstract