Michael Kompitsas - Academia.edu (original) (raw)
Papers by Michael Kompitsas
Phase conjugation by degenerate four-wave mixing in absorbing media
IEEE Journal of Quantum Electronics, 1982
A theory describing degenerate four-wave mixing in absorbing media is developed in terms of a gen... more A theory describing degenerate four-wave mixing in absorbing media is developed in terms of a general nonlinear susceptibility. The predictions of the theory are examined in both high and low reflectivity regimes, and the specific nonlinearity-inducting mechanisms of thermally induced refractive index changes, the Kerr effect, and saturable absorption are discussed. A theory of this type is thought to be particularly relevant to degenerate four-wave mixing experiments in the ultraviolet. Predictions from the theory are compared with results obtained from such experiments.
Materials Letters, 2015
Investigation on chalcopyrite structures is crucial for making further progress in thin films tec... more Investigation on chalcopyrite structures is crucial for making further progress in thin films technology. In this work we present the results on optical, electrical and surface properties of CuIn 0.7 Ga 0.3 (Se 0.4 Te 0.6) 2 (CIGSeTe) multinary compounds thin films with annealing effect. The developed procedure is a twosteps methodology involving the pre-reaction of high purity elements Cu, In, Ga, Se and Te in a carbon coated quartz ampoule and e-beam evaporation for thin film deposition. The availability of a multicomponent absorber layers such as CuInGaSeTe, including all elements in a defined ratio, offers the opportunity to reduce film formation temperatures and thereby also reduce manufacturing costs. This aspect was a great motivation to evaluate these materials as banausic and new trend solar cell materials.
A New Nanostructured Multinary Compounds thin film: For photovoltaics
Qualitative determination of organic pollutants in an aquatic environment by laser-induced fluorescence combined with optical fibers
SPIE Proceedings, 1998
The increasing need for the recording and monitoring of the marine pollution, as well as the disa... more The increasing need for the recording and monitoring of the marine pollution, as well as the disadvantages usually presented by the conventional methods to qualitatively and quantitatively determine the pollutants in the marine environment, have led to the development of a new method, which is based on the technique of laser induced fluorescence combined with the use of optical fibers.
![Research paper thumbnail of Comments on the paper “Modulation of period of quantum beats from optical emissions from the excited electronic states of mercury triatomic clusters” by E. Sarantopoulou, et al. (Eds.) [Synth. Met. 124 (2001) 267]](https://attachments.academia-assets.com/102929487/thumbnails/1.jpg)
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Color-Saturated ZnO Deep-Ultraviolet Light Emitters with AlN Server Layer
Journal of Nanoengineering and Nanomanufacturing, 2015
Materials Letters, 2015
Investigation on chalcopyrite structures is crucial for making further progress in thin films tec... more Investigation on chalcopyrite structures is crucial for making further progress in thin films technology. In this work we present the results on optical, electrical and surface properties of CuIn 0.7 Ga 0.3 (Se 0.4 Te 0.6) 2 (CIGSeTe) multinary compounds thin films with annealing effect. The developed procedure is a twosteps methodology involving the pre-reaction of high purity elements Cu, In, Ga, Se and Te in a carbon coated quartz ampoule and e-beam evaporation for thin film deposition. The availability of a multicomponent absorber layers such as CuInGaSeTe, including all elements in a defined ratio, offers the opportunity to reduce film formation temperatures and thereby also reduce manufacturing costs. This aspect was a great motivation to evaluate these materials as banausic and new trend solar cell materials.
Autoionising 4dnf States and Multiphoton Ionisation Studies in Strontium
NATO ASI Series, 1990
In Sr, we report the preliminary data obtained using one-colour and two-colour laser excitations ... more In Sr, we report the preliminary data obtained using one-colour and two-colour laser excitations in an atomic beam associated with a time-of-flight (T.O.F.) ion detection technique. In section 1, the Sr+ yield measured in the range 532–541 nm with the one-colour excitation exhibits many resonance lines. They correspond to 2-photon excitation of bound states and 3-photon excitation of autoionising 4d5f states. Results obtained from a two-colour laser excitation via the 5p2 1D2 bound level improve the resolution and confirm the J-level assignation of the 4d5f states from the one-colour experiment. They extend the observation to other members of the 4dnf series (n = 4 and 6).
Kinetics of gas-phase tropospheric reactions of organic solvents and hydroxyl radical by laser photolysis laser-induced fluorescence
SPIE Proceedings, 1998
Hydroxyl gas-phase reactions play a very important role in air pollution. For the majority of che... more Hydroxyl gas-phase reactions play a very important role in air pollution. For the majority of chemical compounds of the atmosphere, the reaction with OH radical s is an intermediate one, part of a long chain reaction. A laser photolysis-laser induced fluorescence technique has been sued to study OH reaction kinetics with dioxane. The apparatus consists of two synchronized pulsed laser
CN violet-band emission as a time-resolved optical probe of transient temperature induced by laser ablation of type I collagen from bovine Achilles tendon
Laser-Tissue Interactions, Therapeutic Applications, and Photodynamic Therapy, 2001
The B 2(Sigma) +->X2(Sigma) + violet band emission spectrum of CN following laser ablation of ... more The B 2(Sigma) +->X2(Sigma) + violet band emission spectrum of CN following laser ablation of type I collagen was exploited for the estimation of the transient temperature of the plasma plume and consequently of the sample surface considering thermodynamic equilibrium. The temperature dependence upon experimental parameters, such as laser intensity and wavelength as well as delay of gated detection was obtained. The temperature was found to increase with increasing laser intensity and decrease with increasing gated time delay and laser wavelength.
Methane sensing properties of CuxO thin films deposited by pulsed laser deposition
2009 International Semiconductor Device Research Symposium, 2009
ABSTRACT In the present work, undoped CuxO thin films were deposited by pulsed laser deposition o... more ABSTRACT In the present work, undoped CuxO thin films were deposited by pulsed laser deposition on glass and SiO2 substrates, at a constant oxygen partial pressure of 40Pa and at constant temperature of 200°C. The surface morphology of the deposited thin films was investigated by atomic force microscopy (AFM) in contact mode. The paper shows the 3D AFM images of CuxO thin films deposited on glass and SiO2 substrate, respectively. We noted that the substrate type had an effect on the surface morphology of the films; the one on glass substrate was smoother than the other on SiO2 substrate with an average roughness around 6nm for a scanning area of 2¿mx2¿m.
Hydrogen gas sensing application of Al/NiO Schottky diode
2008 IEEE Sensors, 2008
Undoped p-type NiO thin film has been developed on high resistivity Si substrates by reactive pul... more Undoped p-type NiO thin film has been developed on high resistivity Si substrates by reactive pulsed laser deposition technique (RPLD). Subsequently an Al/NiO Schottky diode has been fabricated by electron gun evaporation and was functionalized as H2 gas sensor.
Hydrogenated amorphous silicon films grown by pulsed laser deposition
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT form only given. Amorphous hydrogenated Si (a-Si:H) thin-film solar cells offer power co... more ABSTRACT form only given. Amorphous hydrogenated Si (a-Si:H) thin-film solar cells offer power conversion efficiencies up to 12% and use the advantage of the existing infrastructure of Si industry, therefore they are of high technologic interest. Moreover, amorphous Si is cost-effective compared to crystalline Si and it is only needed in small quantities for thin-film solar cell production on rigid or flexible substrates. Pulsed laser deposition (PLD) is a simple, versatile, and cost-effective technique [1] for the deposition of a-Si:H layers.We employ pulsed laser deposition for the fabrication of a-Si:H solar cells in the p-i-n configuration for increased efficiency, as shown in Fig. 1, because the short minority-carrier lifetime in a-Si:H, especially in the doped varieties, requires electric field assistance for efficient collection of photogenerated carriers. The efficiency of the solar cell can be further improved by the incorporation of metallic nanoparticles for increased light absoprtion [2,3]. We irradiate silicon targets by a large number of laser pulses produced by an Nd:YAG laser system (10 ns pulse duration), operating at 355 nm in hydrogen atmosphere. In order to achieve doping for the n-type and p-type layers, we use highly doped silicon targets. Varying the PLD parameters, such as the laser fluence, number of pulses, substrate temperature, and hydrogen pressure, we optimize the morphology, electric conductivity, and optical properties of the a-Si:H layers for maximum efficiency.The conductivity of the a-Si:H films depends strongly on the laser fluence, while the optical absorption depends on the hydrogen pressure during deposition. The doping level of the a-Si:H layers can be further controlled by the simultaneous irradiation of the silicon target and a doping target by two synchronized lasers [4]. Post-deposition annealing also improves the properties of the deposited films.
12th International School on Quantum Electronics: Laser Physics and Applications, 2003
ABSTRACT Pulsed laser deposition of thin films has besides numerous advantages a major shortcomin... more ABSTRACT Pulsed laser deposition of thin films has besides numerous advantages a major shortcoming which is the presence of particulates of various shapes and dimensions both on surface and inside obtained structures. Indeed, in many key technological applications the use of completely particulates free films is mandatory. We demonstrated that the origin of size and density of particulates depend on specific experimental conditions. Nevertheless, the proper choice of deposition conditions (i.e. ablating laser wavelength and fluence, target-collector separation distance, growing temperature, ambient gas nature and pressure) allows for the decrease under a certain extent of pollution with particulates, but not for their complete elimination. This lecture reports our successful attempts to obtain completely particulates free deposited structures using two synchronized pulsed laser sources. The first, UV laser source was used to ablate the target material. The second, IR laser system was directed parallel to the target surface. The role of the second laser was to heat and vaporize the particulates present in the tail of the plasma ablated by the pulsed UV laser source.
Growth of metal-oxide semiconductor nanocomposite thin films by a dual-laser, dual target deposition system
Thin Solid Films, 2007
ABSTRACT Nanocomposite formed by gold nanoparticles embedded in a titanium dioxide matrix thin fi... more ABSTRACT Nanocomposite formed by gold nanoparticles embedded in a titanium dioxide matrix thin films have been synthesized by a synchronized two laser system. An ArF⁎ excimer (λ=193 nm, τFWHM ∼12 ns) laser and a frequency tripled Nd:Yttrium Aluminium Garnet (YAG; λ=355 nm, τFWHM ∼10 ns) laser were used for the irradiation of titanium dioxide and gold targets. The investigations showed that there exists the possibility for tailoring the optical properties of gold-titanium dioxide nanocomposites by the proper choice of the laser irradiation parameters. The band gap narrowing and additional absorption in the visible spectral region induced by the incorporation of gold in the host TiO2 matrix allows for the design of nanostructured thin films for new generation of photocatalysts or solar energy converters.
Effects of post-deposition surface treatment on the optical, structural and hydrogen sensing properties of TiO2 thin films
Thin Solid Films, 2009
ABSTRACT TiO2 thin films were prepared by DC reactive magnetron sputtering in a mixture of oxygen... more ABSTRACT TiO2 thin films were prepared by DC reactive magnetron sputtering in a mixture of oxygen and argon on glass and oxidized silicon substrates. The effect of post-deposition annealing (300 °C, 500 °C and 700 °C for 8 h in air) on the structural and morphological properties of TiO2 thin films is presented. In addition, the effect of Pt surface modification (1, 3 and 5 nm) on hydrogen sensing was studied. XRD patterns have shown that in the range of annealing temperatures from 300 °C to 500 °C crystallization starts and the thin film structure changes from amorphous to polycrystalline (anatase phase). In the case of samples on glass substrate, optical transmittance spectra were recorded. TiO2 thin films were tested as sensors of hydrogen at concentrations 10,000–1000 ppm and operating temperatures within the 180–200 °C range. The samples with 1 nm and in particular with 3 nm of Pt on the surface responded to hydrogen fast and with high sensitivity.
Spectrochimica Acta Part B: Atomic Spectroscopy, 2001
Calibration curves for the elements Cr, Ni and Mn in commercial steel alloy samples were obtained... more Calibration curves for the elements Cr, Ni and Mn in commercial steel alloy samples were obtained employing the Internal Standardization method in atmospheric air pressure. A number of experimental parameters have been optimized in order that the produced calibration curves showed good linearity over a broad range of concentrations covered by the alloy elements. Emphasis was given to the development of the method for field analysis and for the on-line control of production processes.
CO-Sensing Properties of CuxO-Based Nanostructured Thin Films Grown by Reactive Pulsed Laser Deposition
Sensor Letters, 2013
ABSTRACT Undoped copper oxides (Cu2O and CuO) thin films were grown by reactive pulsed laser depo... more ABSTRACT Undoped copper oxides (Cu2O and CuO) thin films were grown by reactive pulsed laser deposition on SiO2 substrates at 20 and 40 Pa oxygen pressures and deposition temperature of 120 °C. The surface morphological and structural properties of the obtained thin films were investigated by Atomic Force Microscopy (AFM) and by Scanning Electron Microscopy (SEM), respectively. Furthermore the CuxO nanostructured thin films were tested as potential carbon monoxide (CO) sensing layers towards two concentrations, 3000 and 5000 ppm CO in air flow, at selected operating temperatures between 150-200 °C. The influence of the oxygen partial pressure on the structural, electrical and gas sensing properties of the films was examined.
Optics Communications, 1985
The small signal gain of a 1:2 molecular laser near 157 nm was measured with the passive cell abs... more The small signal gain of a 1:2 molecular laser near 157 nm was measured with the passive cell absorption method. A gain of 3.2% cm i v.as found under optimum working conditions at 2 atmtotalgaspres~ure.
Observation and theoretical analysis of the odd J=3 autoionising spectrum of Sr up to the 4d threshold
Journal of Physics B: Atomic, Molecular and Optical Physics, 1990
ABSTRACT The odd J=3 autoionising spectrum of Sr between the 5s and the 4d thresholds has been ob... more ABSTRACT The odd J=3 autoionising spectrum of Sr between the 5s and the 4d thresholds has been observed. In a Sr atomic beam, the ionised atoms produced by a two-step excitation scheme have been analysed via a time-of-flight spectrometer. A theoretical approach based on the R-matrix method combined with multichannel quantum defect theory calculations provided a good description of the position of the observed lines. Analysis of the observed profiles gave qualitatively good results although the intermediate 5p2 1D2 level is not perfectly described in the model.
Phase conjugation by degenerate four-wave mixing in absorbing media
IEEE Journal of Quantum Electronics, 1982
A theory describing degenerate four-wave mixing in absorbing media is developed in terms of a gen... more A theory describing degenerate four-wave mixing in absorbing media is developed in terms of a general nonlinear susceptibility. The predictions of the theory are examined in both high and low reflectivity regimes, and the specific nonlinearity-inducting mechanisms of thermally induced refractive index changes, the Kerr effect, and saturable absorption are discussed. A theory of this type is thought to be particularly relevant to degenerate four-wave mixing experiments in the ultraviolet. Predictions from the theory are compared with results obtained from such experiments.
Materials Letters, 2015
Investigation on chalcopyrite structures is crucial for making further progress in thin films tec... more Investigation on chalcopyrite structures is crucial for making further progress in thin films technology. In this work we present the results on optical, electrical and surface properties of CuIn 0.7 Ga 0.3 (Se 0.4 Te 0.6) 2 (CIGSeTe) multinary compounds thin films with annealing effect. The developed procedure is a twosteps methodology involving the pre-reaction of high purity elements Cu, In, Ga, Se and Te in a carbon coated quartz ampoule and e-beam evaporation for thin film deposition. The availability of a multicomponent absorber layers such as CuInGaSeTe, including all elements in a defined ratio, offers the opportunity to reduce film formation temperatures and thereby also reduce manufacturing costs. This aspect was a great motivation to evaluate these materials as banausic and new trend solar cell materials.
A New Nanostructured Multinary Compounds thin film: For photovoltaics
Qualitative determination of organic pollutants in an aquatic environment by laser-induced fluorescence combined with optical fibers
SPIE Proceedings, 1998
The increasing need for the recording and monitoring of the marine pollution, as well as the disa... more The increasing need for the recording and monitoring of the marine pollution, as well as the disadvantages usually presented by the conventional methods to qualitatively and quantitatively determine the pollutants in the marine environment, have led to the development of a new method, which is based on the technique of laser induced fluorescence combined with the use of optical fibers.
Color-Saturated ZnO Deep-Ultraviolet Light Emitters with AlN Server Layer
Journal of Nanoengineering and Nanomanufacturing, 2015
Materials Letters, 2015
Investigation on chalcopyrite structures is crucial for making further progress in thin films tec... more Investigation on chalcopyrite structures is crucial for making further progress in thin films technology. In this work we present the results on optical, electrical and surface properties of CuIn 0.7 Ga 0.3 (Se 0.4 Te 0.6) 2 (CIGSeTe) multinary compounds thin films with annealing effect. The developed procedure is a twosteps methodology involving the pre-reaction of high purity elements Cu, In, Ga, Se and Te in a carbon coated quartz ampoule and e-beam evaporation for thin film deposition. The availability of a multicomponent absorber layers such as CuInGaSeTe, including all elements in a defined ratio, offers the opportunity to reduce film formation temperatures and thereby also reduce manufacturing costs. This aspect was a great motivation to evaluate these materials as banausic and new trend solar cell materials.
Autoionising 4dnf States and Multiphoton Ionisation Studies in Strontium
NATO ASI Series, 1990
In Sr, we report the preliminary data obtained using one-colour and two-colour laser excitations ... more In Sr, we report the preliminary data obtained using one-colour and two-colour laser excitations in an atomic beam associated with a time-of-flight (T.O.F.) ion detection technique. In section 1, the Sr+ yield measured in the range 532–541 nm with the one-colour excitation exhibits many resonance lines. They correspond to 2-photon excitation of bound states and 3-photon excitation of autoionising 4d5f states. Results obtained from a two-colour laser excitation via the 5p2 1D2 bound level improve the resolution and confirm the J-level assignation of the 4d5f states from the one-colour experiment. They extend the observation to other members of the 4dnf series (n = 4 and 6).
Kinetics of gas-phase tropospheric reactions of organic solvents and hydroxyl radical by laser photolysis laser-induced fluorescence
SPIE Proceedings, 1998
Hydroxyl gas-phase reactions play a very important role in air pollution. For the majority of che... more Hydroxyl gas-phase reactions play a very important role in air pollution. For the majority of chemical compounds of the atmosphere, the reaction with OH radical s is an intermediate one, part of a long chain reaction. A laser photolysis-laser induced fluorescence technique has been sued to study OH reaction kinetics with dioxane. The apparatus consists of two synchronized pulsed laser
CN violet-band emission as a time-resolved optical probe of transient temperature induced by laser ablation of type I collagen from bovine Achilles tendon
Laser-Tissue Interactions, Therapeutic Applications, and Photodynamic Therapy, 2001
The B 2(Sigma) +->X2(Sigma) + violet band emission spectrum of CN following laser ablation of ... more The B 2(Sigma) +->X2(Sigma) + violet band emission spectrum of CN following laser ablation of type I collagen was exploited for the estimation of the transient temperature of the plasma plume and consequently of the sample surface considering thermodynamic equilibrium. The temperature dependence upon experimental parameters, such as laser intensity and wavelength as well as delay of gated detection was obtained. The temperature was found to increase with increasing laser intensity and decrease with increasing gated time delay and laser wavelength.
Methane sensing properties of CuxO thin films deposited by pulsed laser deposition
2009 International Semiconductor Device Research Symposium, 2009
ABSTRACT In the present work, undoped CuxO thin films were deposited by pulsed laser deposition o... more ABSTRACT In the present work, undoped CuxO thin films were deposited by pulsed laser deposition on glass and SiO2 substrates, at a constant oxygen partial pressure of 40Pa and at constant temperature of 200°C. The surface morphology of the deposited thin films was investigated by atomic force microscopy (AFM) in contact mode. The paper shows the 3D AFM images of CuxO thin films deposited on glass and SiO2 substrate, respectively. We noted that the substrate type had an effect on the surface morphology of the films; the one on glass substrate was smoother than the other on SiO2 substrate with an average roughness around 6nm for a scanning area of 2¿mx2¿m.
Hydrogen gas sensing application of Al/NiO Schottky diode
2008 IEEE Sensors, 2008
Undoped p-type NiO thin film has been developed on high resistivity Si substrates by reactive pul... more Undoped p-type NiO thin film has been developed on high resistivity Si substrates by reactive pulsed laser deposition technique (RPLD). Subsequently an Al/NiO Schottky diode has been fabricated by electron gun evaporation and was functionalized as H2 gas sensor.
Hydrogenated amorphous silicon films grown by pulsed laser deposition
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT form only given. Amorphous hydrogenated Si (a-Si:H) thin-film solar cells offer power co... more ABSTRACT form only given. Amorphous hydrogenated Si (a-Si:H) thin-film solar cells offer power conversion efficiencies up to 12% and use the advantage of the existing infrastructure of Si industry, therefore they are of high technologic interest. Moreover, amorphous Si is cost-effective compared to crystalline Si and it is only needed in small quantities for thin-film solar cell production on rigid or flexible substrates. Pulsed laser deposition (PLD) is a simple, versatile, and cost-effective technique [1] for the deposition of a-Si:H layers.We employ pulsed laser deposition for the fabrication of a-Si:H solar cells in the p-i-n configuration for increased efficiency, as shown in Fig. 1, because the short minority-carrier lifetime in a-Si:H, especially in the doped varieties, requires electric field assistance for efficient collection of photogenerated carriers. The efficiency of the solar cell can be further improved by the incorporation of metallic nanoparticles for increased light absoprtion [2,3]. We irradiate silicon targets by a large number of laser pulses produced by an Nd:YAG laser system (10 ns pulse duration), operating at 355 nm in hydrogen atmosphere. In order to achieve doping for the n-type and p-type layers, we use highly doped silicon targets. Varying the PLD parameters, such as the laser fluence, number of pulses, substrate temperature, and hydrogen pressure, we optimize the morphology, electric conductivity, and optical properties of the a-Si:H layers for maximum efficiency.The conductivity of the a-Si:H films depends strongly on the laser fluence, while the optical absorption depends on the hydrogen pressure during deposition. The doping level of the a-Si:H layers can be further controlled by the simultaneous irradiation of the silicon target and a doping target by two synchronized lasers [4]. Post-deposition annealing also improves the properties of the deposited films.
12th International School on Quantum Electronics: Laser Physics and Applications, 2003
ABSTRACT Pulsed laser deposition of thin films has besides numerous advantages a major shortcomin... more ABSTRACT Pulsed laser deposition of thin films has besides numerous advantages a major shortcoming which is the presence of particulates of various shapes and dimensions both on surface and inside obtained structures. Indeed, in many key technological applications the use of completely particulates free films is mandatory. We demonstrated that the origin of size and density of particulates depend on specific experimental conditions. Nevertheless, the proper choice of deposition conditions (i.e. ablating laser wavelength and fluence, target-collector separation distance, growing temperature, ambient gas nature and pressure) allows for the decrease under a certain extent of pollution with particulates, but not for their complete elimination. This lecture reports our successful attempts to obtain completely particulates free deposited structures using two synchronized pulsed laser sources. The first, UV laser source was used to ablate the target material. The second, IR laser system was directed parallel to the target surface. The role of the second laser was to heat and vaporize the particulates present in the tail of the plasma ablated by the pulsed UV laser source.
Growth of metal-oxide semiconductor nanocomposite thin films by a dual-laser, dual target deposition system
Thin Solid Films, 2007
ABSTRACT Nanocomposite formed by gold nanoparticles embedded in a titanium dioxide matrix thin fi... more ABSTRACT Nanocomposite formed by gold nanoparticles embedded in a titanium dioxide matrix thin films have been synthesized by a synchronized two laser system. An ArF⁎ excimer (λ=193 nm, τFWHM ∼12 ns) laser and a frequency tripled Nd:Yttrium Aluminium Garnet (YAG; λ=355 nm, τFWHM ∼10 ns) laser were used for the irradiation of titanium dioxide and gold targets. The investigations showed that there exists the possibility for tailoring the optical properties of gold-titanium dioxide nanocomposites by the proper choice of the laser irradiation parameters. The band gap narrowing and additional absorption in the visible spectral region induced by the incorporation of gold in the host TiO2 matrix allows for the design of nanostructured thin films for new generation of photocatalysts or solar energy converters.
Effects of post-deposition surface treatment on the optical, structural and hydrogen sensing properties of TiO2 thin films
Thin Solid Films, 2009
ABSTRACT TiO2 thin films were prepared by DC reactive magnetron sputtering in a mixture of oxygen... more ABSTRACT TiO2 thin films were prepared by DC reactive magnetron sputtering in a mixture of oxygen and argon on glass and oxidized silicon substrates. The effect of post-deposition annealing (300 °C, 500 °C and 700 °C for 8 h in air) on the structural and morphological properties of TiO2 thin films is presented. In addition, the effect of Pt surface modification (1, 3 and 5 nm) on hydrogen sensing was studied. XRD patterns have shown that in the range of annealing temperatures from 300 °C to 500 °C crystallization starts and the thin film structure changes from amorphous to polycrystalline (anatase phase). In the case of samples on glass substrate, optical transmittance spectra were recorded. TiO2 thin films were tested as sensors of hydrogen at concentrations 10,000–1000 ppm and operating temperatures within the 180–200 °C range. The samples with 1 nm and in particular with 3 nm of Pt on the surface responded to hydrogen fast and with high sensitivity.
Spectrochimica Acta Part B: Atomic Spectroscopy, 2001
Calibration curves for the elements Cr, Ni and Mn in commercial steel alloy samples were obtained... more Calibration curves for the elements Cr, Ni and Mn in commercial steel alloy samples were obtained employing the Internal Standardization method in atmospheric air pressure. A number of experimental parameters have been optimized in order that the produced calibration curves showed good linearity over a broad range of concentrations covered by the alloy elements. Emphasis was given to the development of the method for field analysis and for the on-line control of production processes.
CO-Sensing Properties of CuxO-Based Nanostructured Thin Films Grown by Reactive Pulsed Laser Deposition
Sensor Letters, 2013
ABSTRACT Undoped copper oxides (Cu2O and CuO) thin films were grown by reactive pulsed laser depo... more ABSTRACT Undoped copper oxides (Cu2O and CuO) thin films were grown by reactive pulsed laser deposition on SiO2 substrates at 20 and 40 Pa oxygen pressures and deposition temperature of 120 °C. The surface morphological and structural properties of the obtained thin films were investigated by Atomic Force Microscopy (AFM) and by Scanning Electron Microscopy (SEM), respectively. Furthermore the CuxO nanostructured thin films were tested as potential carbon monoxide (CO) sensing layers towards two concentrations, 3000 and 5000 ppm CO in air flow, at selected operating temperatures between 150-200 °C. The influence of the oxygen partial pressure on the structural, electrical and gas sensing properties of the films was examined.
Optics Communications, 1985
The small signal gain of a 1:2 molecular laser near 157 nm was measured with the passive cell abs... more The small signal gain of a 1:2 molecular laser near 157 nm was measured with the passive cell absorption method. A gain of 3.2% cm i v.as found under optimum working conditions at 2 atmtotalgaspres~ure.
Observation and theoretical analysis of the odd J=3 autoionising spectrum of Sr up to the 4d threshold
Journal of Physics B: Atomic, Molecular and Optical Physics, 1990
ABSTRACT The odd J=3 autoionising spectrum of Sr between the 5s and the 4d thresholds has been ob... more ABSTRACT The odd J=3 autoionising spectrum of Sr between the 5s and the 4d thresholds has been observed. In a Sr atomic beam, the ionised atoms produced by a two-step excitation scheme have been analysed via a time-of-flight spectrometer. A theoretical approach based on the R-matrix method combined with multichannel quantum defect theory calculations provided a good description of the position of the observed lines. Analysis of the observed profiles gave qualitatively good results although the intermediate 5p2 1D2 level is not perfectly described in the model.