Bich Vu Thi - Academia.edu (original) (raw)

Papers by Bich Vu Thi

Research paper thumbnail of Sn doped Hematite Nanorods for High-Performance Photoelectrochemical Water Splitting

Vietnam Journal of Catalysis and Adsorption

Photoelectrochemical water splitting is of great attention due to its environmentally friendly ge... more Photoelectrochemical water splitting is of great attention due to its environmentally friendly generation of clean fuels. Hematite (α-Fe2O3) is considered a promising candidate due to its intrinsic properties for the high-performance photoelectrochemical electrode, such as favorable bandgap (2.0–2.2 eV), a suitable energy band position non-toxicity, low cost, and excellent chemical stability. Herein, we report about Sn-doped hematite nanorods and their implementation as photoanodes for photoelectrochemical water splitting. We provide the simple but efficient route to incorporate the Sn into the hematite without structural damage in the nanostructure and scrutinize the effect of Sn dopant on the photoelectrochemical activity of the hematite. Sn can be successfully incorporated into the hematite by the two-step heat treatment process, which reveals the enhanced photoelectrochemical responses compared with undoped hematite. We elaborate on the effect of Sn dopant in the hematite on th...

Research paper thumbnail of CuS–CdS@TiO2 multi-heterostructure-based photoelectrode for highly efficient photoelectrochemical water splitting

Research paper thumbnail of The 3D Hierarchical Structure of ZnO@CdS Core-Shell Nanorods on WO3 Nanoplates for High-Performance Hydrogen Production

ECS Journal of Solid State Science and Technology

Hydrogen evolution by water splitting is one of the easy and clean methods for generating energy ... more Hydrogen evolution by water splitting is one of the easy and clean methods for generating energy that can solve the energy crisis in the near future. In this report, WO3 nanoplates were treated with a chemical bath deposition (CBD) and hydrothermal (HM) sequentially to synthesize the ZnO@CdS core-shell nanorods (NRs) on the nanoplates. Prior to this, the sputtering process followed by HM has been involved to grow basic uniform WO3 NPts onto the FTO substrate. To ensure the enhancement in the performance of the photoanode under solar light, the sputtered-grown Pt nanoparticles were used as the catalyst. The method measurements FESEM, HR-TEM, XRD, LSV, and conversion efficiency were used for the examination of the morphology and performance of the photoanodes. In an aqueous solution of 0.3 M Na2S and 0.2 M Na2SO3 (pH ∼13.5), the linear sweep voltammetry (LSV) analysis shows a photocurrent density of 17.1 mA cm−2 at 0 V vs SCE and 6.1% of the efficiency of conversion energy at −0.5 V v...

Research paper thumbnail of Diffusion of fluorescent molecules and quantum dot nanoparticles in viscous solvents investigated by fluorescence correlation spectroscopy

Vietnam Journal of Chemistry, 2018

The fluorescence correlation spectroscopy (FCS) is a powerful measurement technique allowing the ... more The fluorescence correlation spectroscopy (FCS) is a powerful measurement technique allowing the study of dynamic properties of fluorescent molecules and nanoparticles in solution environment with high sensitivity down to single molecule/particle level. In this paper we investigate the diffusion of Rhodamine B molecules and fluorescent quantum dots in solvents with different viscosities using a FCS instrument. The measured correlation functions show that the diffusion times of all molecules and quantum dots increase with the solvent viscosity. From the experimental data we derive the diffusion coefficients and hydrodynamic radii of the dye molecules and nanoparticles in different solvents using the Stokes-Einstein relation. Our results show that the diffusion times depend linearly on the solvent viscosity while the hydrodynamic radii remain approximately constant. The results will be useful for further study of the dynamics of molecules and nanoparticles in various biological environments.

Research paper thumbnail of Study by optical multichannel analysis of the electrochromic phenomena in polyaniline doped with camphorsulfonic acid

Synthetic Metals, 1996

The possibility of protonation of polyaniline (PANI) by functionalized acids such as camphorsulfo... more The possibility of protonation of polyaniline (PANI) by functionalized acids such as camphorsulfonic acid (HCSA) is one of the most outstanding recent results about this conducting polymer. Here, optical multichannel analysis (OMA) is used to characterize the optical properties of PANI-CSA during its polarization in an electrochromic cell. Compared with PANI doped in usual mineral acid solutions, PANI-CSA displays a remarkable stability during the electrochromic cyclings.

Research paper thumbnail of INVESTIGATION OF ZnO NANO STRUCTURES FABRICATED ON AL2O3 SUBSTRACTES BY MOCVD

ASEAN Journal on Science and Technology for Development, 2017

High quality ZnO nanostructures were grown directly on sapphire subtracts by metal organic vapor ... more High quality ZnO nanostructures were grown directly on sapphire subtracts by metal organic vapor deposition. By changing the growth conditions, the different nano structures (nanorods,nanotubes, nanowalls, nanonetworks) can be selectively. These nanostructures were all epitaxially grown and had the same epitaxial relationship with respect to the substrate. Mechanisms corresponding to different nanostructures were discussed. The nanostructures exhibited stable excitonic states at room temperature, and the emission due to exciton-exciton scattering was observed

Research paper thumbnail of Study of the conduction mechanisms at the PANI /PAMPS interface. Role of m-cresol

Synthetic Metals, 1999

The interface between polyaniline (PANI) and a polymer electrolyte (PAMPS) containing functionali... more The interface between polyaniline (PANI) and a polymer electrolyte (PAMPS) containing functionalized sulfonate anions (AMPS) presents a particular structure (doublestrand polymer) allowing the transfer of carriers, even when PANI is oxidized up to an insulating form. The conduction is detected by the growth of an IR optical absorption. The role of a PANI treatment by m-cresol is investigated.

Research paper thumbnail of Vacuum annealing effects on structural and electrical properties of reactively evaporated indium tin oxide

Physica Status Solidi (a), 1988

Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vac... more Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vacuum annealing on the films has been investigated. Various structural, electrical, and optical properties have also been studied. Experimental For doping tin atoms in 1% 03 ...

Research paper thumbnail of Microstructure and Raman Spectra of Tetravalent Metallo- Phthalocyanine

APPC 2000, 2001

The characteristic vibrations of tetravalent metallo -Pc (TiOPc, VOPc) have been studied by Raman... more The characteristic vibrations of tetravalent metallo -Pc (TiOPc, VOPc) have been studied by Raman and resonance Raman spectroscopy. From the relationships between the Raman frequencies of the ring and the metal-ligand distance d (Me- N) established for a large number of the metallo- Pc, the geometry parameter of these molecules is evaluated.

Research paper thumbnail of Optical Properties of \(\text{CuInS}_{2}\) Thin Films Prepared by Spray Pyrolysis

Communications in Physics, 2012

Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolys... more Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolysis of aqueuos solution of copper chloride, indium chloride and thiourea onto heated glass substrates. By optimizing the spray parameters, such as reducing/increasing the temperature of the substrate and molar ratio of Cu/In in the spraying solution, the optical characteristics of films, which are well matched to the solar spectrum, were identified. In all cases, those CIS thin films were of p-type conductivity. Transmission measurements were performed to examine the optical properties of the films; the absorption coefficient and the optical band gap of the films were calculated by transmission spectra. The absorption spectra of the films showed that this compound is a direct band gap one and its gap varied between 1.30 - 1.78 eV. Those thin films were analyzed by X-ray diffraction in order to understand the effect of layers structure on their optical properties.

Research paper thumbnail of Ultrashort Pulse Generation with Micro-Cavity Dye Lasers

APPC 2000, 2001

Abstract: The spectral and laser dynamics of dye laser emissions from low-Q micro-cavities are in... more Abstract: The spectral and laser dynamics of dye laser emissions from low-Q micro-cavities are investigated theoretically and experimentally. The obtained results demonstrate that the ultrashort pulse generation with micro-cavity dye lasers is achieved by some simple ways ...

Research paper thumbnail of Preparation of In2O3:Sn (ITO) Films by Electron Beam Deposition

Physica Status Solidi (a), 1987

Research paper thumbnail of Luminescence properties of II/VI semiconductor colloidal nanocrystals at collective and single scales

Journal of Physics: Conference Series, 2009

Fast timing has emerged as a critical requirement for radiation detection in medical and high ene... more Fast timing has emerged as a critical requirement for radiation detection in medical and high energy physics, motivating the search for scintillator materials with high light yield and fast time response. However, light emission rates from conventional scintillation mechanisms fundamentally limit the achievable time resolution, which is presently at least one order of magnitude slower than required for next-generation detectors. One solution to this challenge is to generate an intense prompt signal in response to ionizing radiation. In this paper, we present colloidal semiconductor nanocrystals (NCs) as promising prompt photon sources. We investigate two classes of NCs: twodimensional CdSe nanoplatelets (NPLs) and spherical CdSe/CdS core/giant shell quantum dots (GS QDs). We demonstrate that the emission rates of these NCs under pulsed X-ray excitation are much faster than traditional mechanisms in bulk scintillators, i.e. 5d-4f transitions. CdSe NPLs have a sub-100 ps effective decay time of 77 ps and CdSe/CdS GS QDs exhibit a sub-ns value of 849 ps. Further, the respective CdSe NPL and CdSe/CdS GS QD X-ray excited photoluminescence have the emission characteristics of excitons (X) and multiexcitons (MX), with the MXs providing additional prospects for fast timing with substantially shorter lifetimes.

Research paper thumbnail of Aerosol Distribution of ASEAN Area Base on LIDAR Monitoring Data at Hanoi and Trajectory Statistics Simulation

Journal of Physical Science and Application, 2016

Averaged fractional composition of aerosol in Vietnam and Belarus was obtained and the maps of th... more Averaged fractional composition of aerosol in Vietnam and Belarus was obtained and the maps of the column on near-ground aerosol content were built on the basics of model calculations. The results show the complexity of the geographic ASEAN areas. It may cause variable of climate in local.

Research paper thumbnail of <title>Raman resonances in sulfonate or Cl-doped PANI films</title>

Optical Probes of Conjugated Polymers, 1997

ABSTRACT The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present v... more ABSTRACT The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few differences with the spectra obtained after doping by inorganic anions, in spite of the noticeable differences displayed elsewhere by their optical spectra: the 3 eV (localized polaron) as well as 1.5 eV bands are stronger and sharper in presence of sulfonate. In fact, during the study of the different PANI forms, it was observed that the connections between Raman and optical features are far from being straight; a simple analysis in terms of the resonance in either benzoid or quinoid units is not enough. To arrive to a better understanding of these connections, we have compared the Raman spectra obtained with blue (localized polaron excitation), red (excitonic resonance) and near-IR (intrachain excitations resonance) lines; with the green laser line, PANI is out of resonance. Spectra were also obtained on samples treated to present a `secondary doping&#39;, and therefore a strong IR absorption. The use of red and IR lights allows to study the splitting of the C equals N peak, which can clearly be decomposed in two sub-bands, as well as the splitting of the 1330 cm-1 peak (assumed to be due to the stretching of C - N+$CCL).

Research paper thumbnail of Electrochromic properties of manganese oxide (MnOx) thin films made by electron beam deposition

Physica Status Solidi (a), 1993

Electrochromic MnO, thin films are prepared by using an electron beam technique followed by annea... more Electrochromic MnO, thin films are prepared by using an electron beam technique followed by annealing post-treatment. Electrochromic properties of the films are studied in three different solutions: 1M LiCIO, in propylene carbonate, KOH (pH = 10.5), and natrium borate (pH = 9.2). The transmittance spectra of the coloured films combined with their cyclic voltammetry curves show that the enhancement of the electrochromic behaviour of these films can be attributed to the insertion (or extraction) of the OHanions into (or from) the MnO, films. The best electrochromic efficiency of the films is obtained in the borate electrolyte.

Research paper thumbnail of Resonant Raman identification of the polaronic organization in PANI

Synthetic Metals, 1999

All solid state electrochromic devices (ECD) using polyaniline (PANI) and W03 separated by a poly... more All solid state electrochromic devices (ECD) using polyaniline (PANI) and W03 separated by a polymer electrolyte, PAMPS, were studied by Raman spectroscopy. The use of a blue laser line allows to isolate the spectral features corresponding to reduced PANI and in particular to follow the fust steps of the charge mechanisms. On the contrary, the red line allows to investigate the phenomena. associated to the oxidized and charged forms of polyaniline, and the formation of bronze in the WO3 electrode. In such devices with several layers, the use of different laser lines allows therefore to separate the reactions in the different electrooptically active media.

Research paper thumbnail of Vacuum annealing effects on structural and electrical properties of reactively evaporated indium tin oxide

Physica Status Solidi (a), 1988

Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vac... more Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vacuum annealing on the films has been investigated. Various structural, electrical, and optical properties have also been studied. Experimental For doping tin atoms in 1% 03 ...

Research paper thumbnail of Preparation of In2O3:Sn (ITO) Films by Electron Beam Deposition

Physica Status Solidi (a), 1987

Research paper thumbnail of Raman resonances in sulfonate or Cl-doped PANI films

The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few d... more The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few differences with the spectra obtained after doping by inorganic anions, in spite of the noticeable differences displayed elsewhere by their optical spectra: the 3 eV (localized polaron) as well as 1.5 eV bands are stronger and sharper in presence of sulfonate. In fact, during the study of the different PANI forms, it was observed that the connections between Raman and optical features are far from being straight; a simple analysis in terms of the resonance in either benzoid or quinoid units is not enough. To arrive to a better understanding of these connections, we have compared the Raman spectra obtained with blue (localized polaron excitation), red (excitonic resonance) and near-IR (intrachain excitations resonance) lines; with the green laser line, PANI is out of resonance. Spectra were also obtained on samples treated to present a `secondary doping', and therefore a strong IR abs...

Research paper thumbnail of Sn doped Hematite Nanorods for High-Performance Photoelectrochemical Water Splitting

Vietnam Journal of Catalysis and Adsorption

Photoelectrochemical water splitting is of great attention due to its environmentally friendly ge... more Photoelectrochemical water splitting is of great attention due to its environmentally friendly generation of clean fuels. Hematite (α-Fe2O3) is considered a promising candidate due to its intrinsic properties for the high-performance photoelectrochemical electrode, such as favorable bandgap (2.0–2.2 eV), a suitable energy band position non-toxicity, low cost, and excellent chemical stability. Herein, we report about Sn-doped hematite nanorods and their implementation as photoanodes for photoelectrochemical water splitting. We provide the simple but efficient route to incorporate the Sn into the hematite without structural damage in the nanostructure and scrutinize the effect of Sn dopant on the photoelectrochemical activity of the hematite. Sn can be successfully incorporated into the hematite by the two-step heat treatment process, which reveals the enhanced photoelectrochemical responses compared with undoped hematite. We elaborate on the effect of Sn dopant in the hematite on th...

Research paper thumbnail of CuS–CdS@TiO2 multi-heterostructure-based photoelectrode for highly efficient photoelectrochemical water splitting

Research paper thumbnail of The 3D Hierarchical Structure of ZnO@CdS Core-Shell Nanorods on WO3 Nanoplates for High-Performance Hydrogen Production

ECS Journal of Solid State Science and Technology

Hydrogen evolution by water splitting is one of the easy and clean methods for generating energy ... more Hydrogen evolution by water splitting is one of the easy and clean methods for generating energy that can solve the energy crisis in the near future. In this report, WO3 nanoplates were treated with a chemical bath deposition (CBD) and hydrothermal (HM) sequentially to synthesize the ZnO@CdS core-shell nanorods (NRs) on the nanoplates. Prior to this, the sputtering process followed by HM has been involved to grow basic uniform WO3 NPts onto the FTO substrate. To ensure the enhancement in the performance of the photoanode under solar light, the sputtered-grown Pt nanoparticles were used as the catalyst. The method measurements FESEM, HR-TEM, XRD, LSV, and conversion efficiency were used for the examination of the morphology and performance of the photoanodes. In an aqueous solution of 0.3 M Na2S and 0.2 M Na2SO3 (pH ∼13.5), the linear sweep voltammetry (LSV) analysis shows a photocurrent density of 17.1 mA cm−2 at 0 V vs SCE and 6.1% of the efficiency of conversion energy at −0.5 V v...

Research paper thumbnail of Diffusion of fluorescent molecules and quantum dot nanoparticles in viscous solvents investigated by fluorescence correlation spectroscopy

Vietnam Journal of Chemistry, 2018

The fluorescence correlation spectroscopy (FCS) is a powerful measurement technique allowing the ... more The fluorescence correlation spectroscopy (FCS) is a powerful measurement technique allowing the study of dynamic properties of fluorescent molecules and nanoparticles in solution environment with high sensitivity down to single molecule/particle level. In this paper we investigate the diffusion of Rhodamine B molecules and fluorescent quantum dots in solvents with different viscosities using a FCS instrument. The measured correlation functions show that the diffusion times of all molecules and quantum dots increase with the solvent viscosity. From the experimental data we derive the diffusion coefficients and hydrodynamic radii of the dye molecules and nanoparticles in different solvents using the Stokes-Einstein relation. Our results show that the diffusion times depend linearly on the solvent viscosity while the hydrodynamic radii remain approximately constant. The results will be useful for further study of the dynamics of molecules and nanoparticles in various biological environments.

Research paper thumbnail of Study by optical multichannel analysis of the electrochromic phenomena in polyaniline doped with camphorsulfonic acid

Synthetic Metals, 1996

The possibility of protonation of polyaniline (PANI) by functionalized acids such as camphorsulfo... more The possibility of protonation of polyaniline (PANI) by functionalized acids such as camphorsulfonic acid (HCSA) is one of the most outstanding recent results about this conducting polymer. Here, optical multichannel analysis (OMA) is used to characterize the optical properties of PANI-CSA during its polarization in an electrochromic cell. Compared with PANI doped in usual mineral acid solutions, PANI-CSA displays a remarkable stability during the electrochromic cyclings.

Research paper thumbnail of INVESTIGATION OF ZnO NANO STRUCTURES FABRICATED ON AL2O3 SUBSTRACTES BY MOCVD

ASEAN Journal on Science and Technology for Development, 2017

High quality ZnO nanostructures were grown directly on sapphire subtracts by metal organic vapor ... more High quality ZnO nanostructures were grown directly on sapphire subtracts by metal organic vapor deposition. By changing the growth conditions, the different nano structures (nanorods,nanotubes, nanowalls, nanonetworks) can be selectively. These nanostructures were all epitaxially grown and had the same epitaxial relationship with respect to the substrate. Mechanisms corresponding to different nanostructures were discussed. The nanostructures exhibited stable excitonic states at room temperature, and the emission due to exciton-exciton scattering was observed

Research paper thumbnail of Study of the conduction mechanisms at the PANI /PAMPS interface. Role of m-cresol

Synthetic Metals, 1999

The interface between polyaniline (PANI) and a polymer electrolyte (PAMPS) containing functionali... more The interface between polyaniline (PANI) and a polymer electrolyte (PAMPS) containing functionalized sulfonate anions (AMPS) presents a particular structure (doublestrand polymer) allowing the transfer of carriers, even when PANI is oxidized up to an insulating form. The conduction is detected by the growth of an IR optical absorption. The role of a PANI treatment by m-cresol is investigated.

Research paper thumbnail of Vacuum annealing effects on structural and electrical properties of reactively evaporated indium tin oxide

Physica Status Solidi (a), 1988

Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vac... more Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vacuum annealing on the films has been investigated. Various structural, electrical, and optical properties have also been studied. Experimental For doping tin atoms in 1% 03 ...

Research paper thumbnail of Microstructure and Raman Spectra of Tetravalent Metallo- Phthalocyanine

APPC 2000, 2001

The characteristic vibrations of tetravalent metallo -Pc (TiOPc, VOPc) have been studied by Raman... more The characteristic vibrations of tetravalent metallo -Pc (TiOPc, VOPc) have been studied by Raman and resonance Raman spectroscopy. From the relationships between the Raman frequencies of the ring and the metal-ligand distance d (Me- N) established for a large number of the metallo- Pc, the geometry parameter of these molecules is evaluated.

Research paper thumbnail of Optical Properties of \(\text{CuInS}_{2}\) Thin Films Prepared by Spray Pyrolysis

Communications in Physics, 2012

Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolys... more Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolysis of aqueuos solution of copper chloride, indium chloride and thiourea onto heated glass substrates. By optimizing the spray parameters, such as reducing/increasing the temperature of the substrate and molar ratio of Cu/In in the spraying solution, the optical characteristics of films, which are well matched to the solar spectrum, were identified. In all cases, those CIS thin films were of p-type conductivity. Transmission measurements were performed to examine the optical properties of the films; the absorption coefficient and the optical band gap of the films were calculated by transmission spectra. The absorption spectra of the films showed that this compound is a direct band gap one and its gap varied between 1.30 - 1.78 eV. Those thin films were analyzed by X-ray diffraction in order to understand the effect of layers structure on their optical properties.

Research paper thumbnail of Ultrashort Pulse Generation with Micro-Cavity Dye Lasers

APPC 2000, 2001

Abstract: The spectral and laser dynamics of dye laser emissions from low-Q micro-cavities are in... more Abstract: The spectral and laser dynamics of dye laser emissions from low-Q micro-cavities are investigated theoretically and experimentally. The obtained results demonstrate that the ultrashort pulse generation with micro-cavity dye lasers is achieved by some simple ways ...

Research paper thumbnail of Preparation of In2O3:Sn (ITO) Films by Electron Beam Deposition

Physica Status Solidi (a), 1987

Research paper thumbnail of Luminescence properties of II/VI semiconductor colloidal nanocrystals at collective and single scales

Journal of Physics: Conference Series, 2009

Fast timing has emerged as a critical requirement for radiation detection in medical and high ene... more Fast timing has emerged as a critical requirement for radiation detection in medical and high energy physics, motivating the search for scintillator materials with high light yield and fast time response. However, light emission rates from conventional scintillation mechanisms fundamentally limit the achievable time resolution, which is presently at least one order of magnitude slower than required for next-generation detectors. One solution to this challenge is to generate an intense prompt signal in response to ionizing radiation. In this paper, we present colloidal semiconductor nanocrystals (NCs) as promising prompt photon sources. We investigate two classes of NCs: twodimensional CdSe nanoplatelets (NPLs) and spherical CdSe/CdS core/giant shell quantum dots (GS QDs). We demonstrate that the emission rates of these NCs under pulsed X-ray excitation are much faster than traditional mechanisms in bulk scintillators, i.e. 5d-4f transitions. CdSe NPLs have a sub-100 ps effective decay time of 77 ps and CdSe/CdS GS QDs exhibit a sub-ns value of 849 ps. Further, the respective CdSe NPL and CdSe/CdS GS QD X-ray excited photoluminescence have the emission characteristics of excitons (X) and multiexcitons (MX), with the MXs providing additional prospects for fast timing with substantially shorter lifetimes.

Research paper thumbnail of Aerosol Distribution of ASEAN Area Base on LIDAR Monitoring Data at Hanoi and Trajectory Statistics Simulation

Journal of Physical Science and Application, 2016

Averaged fractional composition of aerosol in Vietnam and Belarus was obtained and the maps of th... more Averaged fractional composition of aerosol in Vietnam and Belarus was obtained and the maps of the column on near-ground aerosol content were built on the basics of model calculations. The results show the complexity of the geographic ASEAN areas. It may cause variable of climate in local.

Research paper thumbnail of <title>Raman resonances in sulfonate or Cl-doped PANI films</title>

Optical Probes of Conjugated Polymers, 1997

ABSTRACT The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present v... more ABSTRACT The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few differences with the spectra obtained after doping by inorganic anions, in spite of the noticeable differences displayed elsewhere by their optical spectra: the 3 eV (localized polaron) as well as 1.5 eV bands are stronger and sharper in presence of sulfonate. In fact, during the study of the different PANI forms, it was observed that the connections between Raman and optical features are far from being straight; a simple analysis in terms of the resonance in either benzoid or quinoid units is not enough. To arrive to a better understanding of these connections, we have compared the Raman spectra obtained with blue (localized polaron excitation), red (excitonic resonance) and near-IR (intrachain excitations resonance) lines; with the green laser line, PANI is out of resonance. Spectra were also obtained on samples treated to present a `secondary doping&#39;, and therefore a strong IR absorption. The use of red and IR lights allows to study the splitting of the C equals N peak, which can clearly be decomposed in two sub-bands, as well as the splitting of the 1330 cm-1 peak (assumed to be due to the stretching of C - N+$CCL).

Research paper thumbnail of Electrochromic properties of manganese oxide (MnOx) thin films made by electron beam deposition

Physica Status Solidi (a), 1993

Electrochromic MnO, thin films are prepared by using an electron beam technique followed by annea... more Electrochromic MnO, thin films are prepared by using an electron beam technique followed by annealing post-treatment. Electrochromic properties of the films are studied in three different solutions: 1M LiCIO, in propylene carbonate, KOH (pH = 10.5), and natrium borate (pH = 9.2). The transmittance spectra of the coloured films combined with their cyclic voltammetry curves show that the enhancement of the electrochromic behaviour of these films can be attributed to the insertion (or extraction) of the OHanions into (or from) the MnO, films. The best electrochromic efficiency of the films is obtained in the borate electrolyte.

Research paper thumbnail of Resonant Raman identification of the polaronic organization in PANI

Synthetic Metals, 1999

All solid state electrochromic devices (ECD) using polyaniline (PANI) and W03 separated by a poly... more All solid state electrochromic devices (ECD) using polyaniline (PANI) and W03 separated by a polymer electrolyte, PAMPS, were studied by Raman spectroscopy. The use of a blue laser line allows to isolate the spectral features corresponding to reduced PANI and in particular to follow the fust steps of the charge mechanisms. On the contrary, the red line allows to investigate the phenomena. associated to the oxidized and charged forms of polyaniline, and the formation of bronze in the WO3 electrode. In such devices with several layers, the use of different laser lines allows therefore to separate the reactions in the different electrooptically active media.

Research paper thumbnail of Vacuum annealing effects on structural and electrical properties of reactively evaporated indium tin oxide

Physica Status Solidi (a), 1988

Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vac... more Recently, we have employed an electron beam technique for depositing IT0 films. The effect of vacuum annealing on the films has been investigated. Various structural, electrical, and optical properties have also been studied. Experimental For doping tin atoms in 1% 03 ...

Research paper thumbnail of Preparation of In2O3:Sn (ITO) Films by Electron Beam Deposition

Physica Status Solidi (a), 1987

Research paper thumbnail of Raman resonances in sulfonate or Cl-doped PANI films

The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few d... more The Raman spectra of polyaniline (PANI) doped by functionalized sulfonic acids present very few differences with the spectra obtained after doping by inorganic anions, in spite of the noticeable differences displayed elsewhere by their optical spectra: the 3 eV (localized polaron) as well as 1.5 eV bands are stronger and sharper in presence of sulfonate. In fact, during the study of the different PANI forms, it was observed that the connections between Raman and optical features are far from being straight; a simple analysis in terms of the resonance in either benzoid or quinoid units is not enough. To arrive to a better understanding of these connections, we have compared the Raman spectra obtained with blue (localized polaron excitation), red (excitonic resonance) and near-IR (intrachain excitations resonance) lines; with the green laser line, PANI is out of resonance. Spectra were also obtained on samples treated to present a `secondary doping', and therefore a strong IR abs...