Anna M Eremenko - Academia.edu (original) (raw)
Papers by Anna M Eremenko
Theoretical and Experimental Chemistry, 1985
ABSTRACT
Theoretical and Experimental Chemistry, 1986
Calculating structural characteristics during investigation of the submicroscopic structure of co... more Calculating structural characteristics during investigation of the submicroscopic structure of concrete by small angle X-ray diffraction analysis," Zh.
Journal of Applied Spectroscopy, 1990
Theoretical and Experimental Chemistry, 1998
ABSTRACT
Research on Chemical Intermediates, 1998
It is shown that an exeiplex between pyrene (Py) and N,N-dimethylaniline (DMA) forms at low tempe... more It is shown that an exeiplex between pyrene (Py) and N,N-dimethylaniline (DMA) forms at low temperature (77 K) on the nonporous silica surface and in a solid hexane solution. The fluorescence lifetime of pyrene in the adsorption state increases when the quencher concentration grows at 77 K. The exciplex fluorescence spectra in the adsorption state shifts to a blue wavelength range when the temperature decreases as a result of the dipole-dipole interaction of the exciplex with the hydroxy groups of the silica surface. On the basis of the model suggested the hydroxyl group concentration on the dehydrated at 770 K silica surface has been estimated.
Journal of Photochemistry and Photobiology A: Chemistry, 2006
The effect of semiconductor titania–silica colloids on the fluorescent properties of adsorbed 4-(... more The effect of semiconductor titania–silica colloids on the fluorescent properties of adsorbed 4-(4′-N, N-diethylaminophenyl-3, 5-dimethyl-1, 7-diphenyl-bis-pyrazolo-[3, 4-b, 3′-e]-pyridine (DEA-DMPP) has been studied by steady-state and time-resolved fluorescence ...
Journal of Molecular Structure, 1992
ABSTRACT
Research on Chemical Intermediates
ABSTRACT
Theoretical and Experimental Chemistry, 2005
We have studied the photocatalytic activity of porous silicas (silica gel, mesoporous sol-gel fil... more We have studied the photocatalytic activity of porous silicas (silica gel, mesoporous sol-gel films) modified by benzophenone molecules, in the reaction of reduction of gold from tetrachloroaurate ions. Stable colloids of nanosized gold were obtained as a result of irradiating aqueous alcoholic solutions of HAuCl 4 •3H 2 O in the presence of the photocatalyst SiO 2-BP using as the stabilizers: a colloidal solution of silica (Ludox) or the surfactant sodium dodecyl sulfate (SDS). We have studied the effect of the stabilizer on the kinetics of the photoreduction reaction, and also on the shape and size of the nanoparticles formed.
Theoretical and Experimental Chemistry, 1982
Journal of Advanced Oxidation Technologies, 2008
The efficiency of nanosized mesoporous TiO 2 , SiO 2 /TiO 2 and SiO 2 films as photocatalytic cov... more The efficiency of nanosized mesoporous TiO 2 , SiO 2 /TiO 2 and SiO 2 films as photocatalytic coverings has been demonstrated by the example of adsorbed acridine orange (AO) dye photodegradation in air. SiO 2-and TiO 2-based functional coatings were prepared via template assisted sol-gel method. The films were characterized by electron microscopy (SEM, TEM), FTIR and UV-Vis spectroscopy. Hydrophylic properties of prepared films were estimated from the water contact angle measurements. Electronic spectra and LDI mass-spectra changes accompanying AO photodegradation under the UV-exposure were investigated and main photodestruction products have been determined. We suggest the photobleach of adsorbed AO on the surface of researched films is a result of the oxidation reaction of dye molecule with the oxygen species such as singlet oxygen and OH • radical produced in the gas phase in presence of titania as well as in presence of sensitizer AO on silica surface. The observed photobleach of AO on the SiO 2 and SiO 2 /TiO 2 films proceeds through the photooxidative Ndemethylation of dimethylaminogroup in dye. Electronic and laser desorption/ionisation mass spectra give evidence that efficient photobleach of AO localized at the surface of anatase films proceeds through the following steps: 1-N-demethylation; 2-photodimerization; 3-photodegradation. Pure commercial TiO 2 P25 (S sp = 50 m 2 /g) does not adsorb some dyes (i.e. Rhodamine 6G (R6G), and process of a mineralization occurs on interface of TiO 2-solution R6G (3). However binary titania-silica catalyst with 10 % TiO 2 and S sp =100 m 2 /g adsorbs R6G from the solution, and process of its mineralization passes much more effectively compared with those on pure TiO 2 powders and coatings (7-10, 13-15). Mesoporous TiO 2 and TiO 2 /ZrO 2 films with developed surface area (400-800m 2 /g) show much higher activity in photoredox destruction of organic pollutants in comparison with their non-porous analogues (15-18). Aminoacridines, the representative acridine dyes, have ubiquitous use as colorant for synthetic fibers, tissue, leather etc (19-24), fluorophores with high fluorescente intensity on hydrophilic surfaces (20, 22, 23). At the same time this dyes represent some of the
Theoretical and Experimental Chemistry
We have used fluorescent spectroscopy and laser flash photolysis to investigate the photonics of ... more We have used fluorescent spectroscopy and laser flash photolysis to investigate the photonics of pyrene molecules in a pyrene–-cyclodextrin inclusion complex in various media. We have observed a protective effect of -cyclodextrin relative to solubilized pyrene molecules during quenching of fluorescence by Ti ions (or titanium dioxide particles) in mixed colloids. In the presence of a precursor of silica (a TEOS solution), the pyrene molecules react with the colloidal silica particles formed, and the reaction is accompanied by decomposition of the pyrene–-cyclodextrin inclusion complex and efficient photoionization of pyrene.
Journal of Applied Spectroscopy, 2010
Electronic spectroscopy and laser desorption/ionization (LDI) mass spectrometry have been used to... more Electronic spectroscopy and laser desorption/ionization (LDI) mass spectrometry have been used to study the effects of UV exposure on acridine dyes such as acridine orange (AO) and acridine yellow (AY) adsorbed on the surface of mesoporous TiO 2 films. The main stages of the photodegradation process have been identified. The first one is photooxidative N-demethylation of the dimethylamino group in AO and deamination in AY. The following stages are photodimerization and photoaggregation on the superhydrophilic TiO 2 surface and further photocatalytic decomposition to the completely mineralized dyes.
Journal of Applied Spectroscopy, 1984
Theoretical and Experimental Chemistry, 1998
Energy diagrams were constructed for CdS nanoparticles doped with silver ions and incorporated in... more Energy diagrams were constructed for CdS nanoparticles doped with silver ions and incorporated into silicate matrices, which are new nanostructural matericds. The effect of the amount of silver introduced on the efficiency of the photocatalytic evolution of hydrogen from aqueous sulfide-sulfite solutions was demonstrated, and the interrelationship between the photocatalytic activity of these materials and their energy characteristics was established.
Theoretical and Experimental Chemistry, 2005
The photocatalytic activity of mesoporous TiO 2 modified by the addition of carbon nanotubes (CNT... more The photocatalytic activity of mesoporous TiO 2 modified by the addition of carbon nanotubes (CNTs) and Cu is reported. Nanocomposites of carbon nanotubes (CNTs) containing varying amounts of Cu were formed by treatment with Cu 2 þ then reduced to Cu 0 using NaBH 4 as the reducing agent. The mesoporous TiO 2 , synthesized by a sol-gel method from titanium isopropoxide, was combined with the CNT/Cu nanocomposites to form the photocatalysts which were characterized by XRD, SEM, TEM, FTIR, XPS and BET surface area analysis. The photocatalytic properties of the mesoporous TiO 2 composites were studied by measuring the degradation of methyl orange (MO) which was optimal in the sample containing 20 wt% of the Cu-CNT nanocomposite. The degradation efficiency for MO was a synergistic effect of photo-degradation of TiO 2 and may be due to improvement of the electrical conductivity of the system by the presence of the CNT/Cu networks, since the photodegradation of MO and the photocatalytic activity of the photoactive systems increased with increasing copper content.
Journal of Applied Spectroscopy, 2014
ABSTRACT Mesoporous titanium dioxide films obtained by the sol/gel template method are used as su... more ABSTRACT Mesoporous titanium dioxide films obtained by the sol/gel template method are used as supports for making TiO2/CdS nanoheterostructures. We show that the photocatalytic method results in formation of smaller CdS nanoparticles than chemical deposition. Photoelectrochemical measurements show more efficient spatial separation of photogenerated charges between components of the photocatalytically produced TiO2/CdS films, and consequently their participation in redox transformation of the xanthene dye Rose Bengal when exposed to UV light leads to higher quantum yields.
NATO Science for Peace and Security Series C: Environmental Security, 2008
The Ag-Au alloy and core-shell bimetallic nanoparticles (BMNP) in colloids can be successfully pr... more The Ag-Au alloy and core-shell bimetallic nanoparticles (BMNP) in colloids can be successfully prepared by photoinduced reduction of correspond-2 a d s (silica film with adsorbed Benzophenone) photocatalyst in water-IPA solution as a source of ketyl radicals and BP anionradicals as the reductive agents, and CTAB as a stabilizer. Generation of BMNP during the photochemical process happens right away of UV-irradiation. The alloy-to-core-shell structure occurs with time (from hours to days) and depends on the order of metal ions photoreduction, viz simultaneous or successive UV irradiation of silver and gold ions in solution, and varying of Ag/Au mole ratio. Ageing of photoproduced colloid nanocomposites accompanied by the change of structure from alloy to core-shell what is proved with UV-vis absorption spectra. Optical spectra demonstrate formation of core-shell structures, where the shell is enriched with the core atoms. For now, first conclusion should be that BMNP Ag:Au 1:1 in colloids are formed mainly with Au NP's in the shell. Photochemically produced and stabilized within pores of silica film Ag/Au BMNPs are formed as separate Ag and Au NP's, together with the big aggregates.
NATO Science for Peace and Security Series C: Environmental Security, 2008
TiO 2 and TiO 2/ZnO films with silver nanoparticles (Ag NP's) distributed in the matrix ... more TiO 2 and TiO 2/ZnO films with silver nanoparticles (Ag NP's) distributed in the matrix and on the surface were characterized by TEM, AFM and UV-Vis spectroscopy. Direct photoelectrochemical investigations of the TiO 2/Ag and TiO 2/ZnO/Ag heterojunctions ...
NATO Science for Peace and Security Series C: Environmental Security, 2008
Mesoporous TiO 2 films were prepared by template assisted sol-gel method and used as support for ... more Mesoporous TiO 2 films were prepared by template assisted sol-gel method and used as support for deposition of CdS particles on its surface to produce visible light sensitive nanocomposites. The influence of the surface morphology of mesoporous titania matrix ...
Theoretical and Experimental Chemistry, 1985
ABSTRACT
Theoretical and Experimental Chemistry, 1986
Calculating structural characteristics during investigation of the submicroscopic structure of co... more Calculating structural characteristics during investigation of the submicroscopic structure of concrete by small angle X-ray diffraction analysis," Zh.
Journal of Applied Spectroscopy, 1990
Theoretical and Experimental Chemistry, 1998
ABSTRACT
Research on Chemical Intermediates, 1998
It is shown that an exeiplex between pyrene (Py) and N,N-dimethylaniline (DMA) forms at low tempe... more It is shown that an exeiplex between pyrene (Py) and N,N-dimethylaniline (DMA) forms at low temperature (77 K) on the nonporous silica surface and in a solid hexane solution. The fluorescence lifetime of pyrene in the adsorption state increases when the quencher concentration grows at 77 K. The exciplex fluorescence spectra in the adsorption state shifts to a blue wavelength range when the temperature decreases as a result of the dipole-dipole interaction of the exciplex with the hydroxy groups of the silica surface. On the basis of the model suggested the hydroxyl group concentration on the dehydrated at 770 K silica surface has been estimated.
Journal of Photochemistry and Photobiology A: Chemistry, 2006
The effect of semiconductor titania–silica colloids on the fluorescent properties of adsorbed 4-(... more The effect of semiconductor titania–silica colloids on the fluorescent properties of adsorbed 4-(4′-N, N-diethylaminophenyl-3, 5-dimethyl-1, 7-diphenyl-bis-pyrazolo-[3, 4-b, 3′-e]-pyridine (DEA-DMPP) has been studied by steady-state and time-resolved fluorescence ...
Journal of Molecular Structure, 1992
ABSTRACT
Research on Chemical Intermediates
ABSTRACT
Theoretical and Experimental Chemistry, 2005
We have studied the photocatalytic activity of porous silicas (silica gel, mesoporous sol-gel fil... more We have studied the photocatalytic activity of porous silicas (silica gel, mesoporous sol-gel films) modified by benzophenone molecules, in the reaction of reduction of gold from tetrachloroaurate ions. Stable colloids of nanosized gold were obtained as a result of irradiating aqueous alcoholic solutions of HAuCl 4 •3H 2 O in the presence of the photocatalyst SiO 2-BP using as the stabilizers: a colloidal solution of silica (Ludox) or the surfactant sodium dodecyl sulfate (SDS). We have studied the effect of the stabilizer on the kinetics of the photoreduction reaction, and also on the shape and size of the nanoparticles formed.
Theoretical and Experimental Chemistry, 1982
Journal of Advanced Oxidation Technologies, 2008
The efficiency of nanosized mesoporous TiO 2 , SiO 2 /TiO 2 and SiO 2 films as photocatalytic cov... more The efficiency of nanosized mesoporous TiO 2 , SiO 2 /TiO 2 and SiO 2 films as photocatalytic coverings has been demonstrated by the example of adsorbed acridine orange (AO) dye photodegradation in air. SiO 2-and TiO 2-based functional coatings were prepared via template assisted sol-gel method. The films were characterized by electron microscopy (SEM, TEM), FTIR and UV-Vis spectroscopy. Hydrophylic properties of prepared films were estimated from the water contact angle measurements. Electronic spectra and LDI mass-spectra changes accompanying AO photodegradation under the UV-exposure were investigated and main photodestruction products have been determined. We suggest the photobleach of adsorbed AO on the surface of researched films is a result of the oxidation reaction of dye molecule with the oxygen species such as singlet oxygen and OH • radical produced in the gas phase in presence of titania as well as in presence of sensitizer AO on silica surface. The observed photobleach of AO on the SiO 2 and SiO 2 /TiO 2 films proceeds through the photooxidative Ndemethylation of dimethylaminogroup in dye. Electronic and laser desorption/ionisation mass spectra give evidence that efficient photobleach of AO localized at the surface of anatase films proceeds through the following steps: 1-N-demethylation; 2-photodimerization; 3-photodegradation. Pure commercial TiO 2 P25 (S sp = 50 m 2 /g) does not adsorb some dyes (i.e. Rhodamine 6G (R6G), and process of a mineralization occurs on interface of TiO 2-solution R6G (3). However binary titania-silica catalyst with 10 % TiO 2 and S sp =100 m 2 /g adsorbs R6G from the solution, and process of its mineralization passes much more effectively compared with those on pure TiO 2 powders and coatings (7-10, 13-15). Mesoporous TiO 2 and TiO 2 /ZrO 2 films with developed surface area (400-800m 2 /g) show much higher activity in photoredox destruction of organic pollutants in comparison with their non-porous analogues (15-18). Aminoacridines, the representative acridine dyes, have ubiquitous use as colorant for synthetic fibers, tissue, leather etc (19-24), fluorophores with high fluorescente intensity on hydrophilic surfaces (20, 22, 23). At the same time this dyes represent some of the
Theoretical and Experimental Chemistry
We have used fluorescent spectroscopy and laser flash photolysis to investigate the photonics of ... more We have used fluorescent spectroscopy and laser flash photolysis to investigate the photonics of pyrene molecules in a pyrene–-cyclodextrin inclusion complex in various media. We have observed a protective effect of -cyclodextrin relative to solubilized pyrene molecules during quenching of fluorescence by Ti ions (or titanium dioxide particles) in mixed colloids. In the presence of a precursor of silica (a TEOS solution), the pyrene molecules react with the colloidal silica particles formed, and the reaction is accompanied by decomposition of the pyrene–-cyclodextrin inclusion complex and efficient photoionization of pyrene.
Journal of Applied Spectroscopy, 2010
Electronic spectroscopy and laser desorption/ionization (LDI) mass spectrometry have been used to... more Electronic spectroscopy and laser desorption/ionization (LDI) mass spectrometry have been used to study the effects of UV exposure on acridine dyes such as acridine orange (AO) and acridine yellow (AY) adsorbed on the surface of mesoporous TiO 2 films. The main stages of the photodegradation process have been identified. The first one is photooxidative N-demethylation of the dimethylamino group in AO and deamination in AY. The following stages are photodimerization and photoaggregation on the superhydrophilic TiO 2 surface and further photocatalytic decomposition to the completely mineralized dyes.
Journal of Applied Spectroscopy, 1984
Theoretical and Experimental Chemistry, 1998
Energy diagrams were constructed for CdS nanoparticles doped with silver ions and incorporated in... more Energy diagrams were constructed for CdS nanoparticles doped with silver ions and incorporated into silicate matrices, which are new nanostructural matericds. The effect of the amount of silver introduced on the efficiency of the photocatalytic evolution of hydrogen from aqueous sulfide-sulfite solutions was demonstrated, and the interrelationship between the photocatalytic activity of these materials and their energy characteristics was established.
Theoretical and Experimental Chemistry, 2005
The photocatalytic activity of mesoporous TiO 2 modified by the addition of carbon nanotubes (CNT... more The photocatalytic activity of mesoporous TiO 2 modified by the addition of carbon nanotubes (CNTs) and Cu is reported. Nanocomposites of carbon nanotubes (CNTs) containing varying amounts of Cu were formed by treatment with Cu 2 þ then reduced to Cu 0 using NaBH 4 as the reducing agent. The mesoporous TiO 2 , synthesized by a sol-gel method from titanium isopropoxide, was combined with the CNT/Cu nanocomposites to form the photocatalysts which were characterized by XRD, SEM, TEM, FTIR, XPS and BET surface area analysis. The photocatalytic properties of the mesoporous TiO 2 composites were studied by measuring the degradation of methyl orange (MO) which was optimal in the sample containing 20 wt% of the Cu-CNT nanocomposite. The degradation efficiency for MO was a synergistic effect of photo-degradation of TiO 2 and may be due to improvement of the electrical conductivity of the system by the presence of the CNT/Cu networks, since the photodegradation of MO and the photocatalytic activity of the photoactive systems increased with increasing copper content.
Journal of Applied Spectroscopy, 2014
ABSTRACT Mesoporous titanium dioxide films obtained by the sol/gel template method are used as su... more ABSTRACT Mesoporous titanium dioxide films obtained by the sol/gel template method are used as supports for making TiO2/CdS nanoheterostructures. We show that the photocatalytic method results in formation of smaller CdS nanoparticles than chemical deposition. Photoelectrochemical measurements show more efficient spatial separation of photogenerated charges between components of the photocatalytically produced TiO2/CdS films, and consequently their participation in redox transformation of the xanthene dye Rose Bengal when exposed to UV light leads to higher quantum yields.
NATO Science for Peace and Security Series C: Environmental Security, 2008
The Ag-Au alloy and core-shell bimetallic nanoparticles (BMNP) in colloids can be successfully pr... more The Ag-Au alloy and core-shell bimetallic nanoparticles (BMNP) in colloids can be successfully prepared by photoinduced reduction of correspond-2 a d s (silica film with adsorbed Benzophenone) photocatalyst in water-IPA solution as a source of ketyl radicals and BP anionradicals as the reductive agents, and CTAB as a stabilizer. Generation of BMNP during the photochemical process happens right away of UV-irradiation. The alloy-to-core-shell structure occurs with time (from hours to days) and depends on the order of metal ions photoreduction, viz simultaneous or successive UV irradiation of silver and gold ions in solution, and varying of Ag/Au mole ratio. Ageing of photoproduced colloid nanocomposites accompanied by the change of structure from alloy to core-shell what is proved with UV-vis absorption spectra. Optical spectra demonstrate formation of core-shell structures, where the shell is enriched with the core atoms. For now, first conclusion should be that BMNP Ag:Au 1:1 in colloids are formed mainly with Au NP's in the shell. Photochemically produced and stabilized within pores of silica film Ag/Au BMNPs are formed as separate Ag and Au NP's, together with the big aggregates.
NATO Science for Peace and Security Series C: Environmental Security, 2008
TiO 2 and TiO 2/ZnO films with silver nanoparticles (Ag NP's) distributed in the matrix ... more TiO 2 and TiO 2/ZnO films with silver nanoparticles (Ag NP's) distributed in the matrix and on the surface were characterized by TEM, AFM and UV-Vis spectroscopy. Direct photoelectrochemical investigations of the TiO 2/Ag and TiO 2/ZnO/Ag heterojunctions ...
NATO Science for Peace and Security Series C: Environmental Security, 2008
Mesoporous TiO 2 films were prepared by template assisted sol-gel method and used as support for ... more Mesoporous TiO 2 films were prepared by template assisted sol-gel method and used as support for deposition of CdS particles on its surface to produce visible light sensitive nanocomposites. The influence of the surface morphology of mesoporous titania matrix ...