The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform

G Auvert - One of the best experts on this subject based on the ideXlab platform.

  • growth kinetics of micron size Nickel lines produced by laser assisted decomposition of Nickel Tetracarbonyl
    Journal of Applied Physics, 1993
    Co-Authors: S Boughaba, G Auvert
    Abstract:

    Polycrystalline Nickel lines as small as 1 μm in width were deposited by pyrolysis of Nickel Tetracarbonyl [Ni(CO)4] on polysilicon/silicon dioxide/monosilicon substrates. As heat source, a cw argon‐ion laser operating at several wavelengths around 0.5 μm was used. The growth kinetics, morphology, and electrical resistivity of the Nickel microstructures were investigated at various scanning speeds of the laser spot, laser beam powers, and reactant gas pressures. From the deposition kinetics, the vertical deposition rate of Nickel was calculated. For Ni(CO)4 pressures below 0.3 mbar, deposition of flat‐topped Nickel lines occurs. The deposition rate was proportional to the Ni(CO)4 pressure and independent of the laser output power. For Ni(CO)4 pressures above 0.3 mbar, lines with a Gaussian profile are obtained. The deposition rate was found to be independent of the Ni(CO)4 pressure and exhibits an activation energy of 11.5 kcal mol−1. The measured electrical resistivity of the flat‐topped lines was about ...

  • deposition of micron size Nickel lines by argon ion laser assisted decomposition of Nickel Tetracarbonyl
    Applied Surface Science, 1993
    Co-Authors: S Boughaba, G Auvert
    Abstract:

    Abstract Nickel lines were deposited from the decomposition of Ni(CO)4 on silicon/silicon-dioxide/silicon substrates locally heated by means of a focused CW argon-ion laser operating at several wavelengths around 0.5 μm. Growth kinetics, morphology and electrical resistivity of the Nickel microstructures were investigated at various scanning speeds of the laser spot, laser beam powers and reactant gas pressures. Nickel lines as small as 1 μm in width were written. From the growth kinetics, the vertical deposition rate of Nickel can be calculated. At low Ni(CO)4 pressures, typically below 0.3 mbar, deposition of flat-topped Nickel lines occurs. The deposition rate is proportional to the Ni(CO)4 pressure and independent of the laser-induced temperature. At reactant gas pressures above 0.3 mbar, Gaussian Nickel lines are obtained. The deposition rate is found to be independent of the Ni(CO)4 pressure and exhibits an activation energy of about 11.5 kcal mol-1. The measured electrical resistivity of the flat-topped lines is about 10 times higher than the bulk resistivity (7 μΩ·cm) while in the Gaussian regime this ratio falls below 1.5. The morphology and roughness of the deposited lines were investigated using both a scanning electron microscope (SEM) and an atomic force microscope (AFM). In the flat-topped regime, grains of about 100 nm are observed at the top of the Nickel lines while in the Gaussian regime the surface is smooth.

S Boughaba - One of the best experts on this subject based on the ideXlab platform.

  • growth kinetics of micron size Nickel lines produced by laser assisted decomposition of Nickel Tetracarbonyl
    Journal of Applied Physics, 1993
    Co-Authors: S Boughaba, G Auvert
    Abstract:

    Polycrystalline Nickel lines as small as 1 μm in width were deposited by pyrolysis of Nickel Tetracarbonyl [Ni(CO)4] on polysilicon/silicon dioxide/monosilicon substrates. As heat source, a cw argon‐ion laser operating at several wavelengths around 0.5 μm was used. The growth kinetics, morphology, and electrical resistivity of the Nickel microstructures were investigated at various scanning speeds of the laser spot, laser beam powers, and reactant gas pressures. From the deposition kinetics, the vertical deposition rate of Nickel was calculated. For Ni(CO)4 pressures below 0.3 mbar, deposition of flat‐topped Nickel lines occurs. The deposition rate was proportional to the Ni(CO)4 pressure and independent of the laser output power. For Ni(CO)4 pressures above 0.3 mbar, lines with a Gaussian profile are obtained. The deposition rate was found to be independent of the Ni(CO)4 pressure and exhibits an activation energy of 11.5 kcal mol−1. The measured electrical resistivity of the flat‐topped lines was about ...

  • deposition of micron size Nickel lines by argon ion laser assisted decomposition of Nickel Tetracarbonyl
    Applied Surface Science, 1993
    Co-Authors: S Boughaba, G Auvert
    Abstract:

    Abstract Nickel lines were deposited from the decomposition of Ni(CO)4 on silicon/silicon-dioxide/silicon substrates locally heated by means of a focused CW argon-ion laser operating at several wavelengths around 0.5 μm. Growth kinetics, morphology and electrical resistivity of the Nickel microstructures were investigated at various scanning speeds of the laser spot, laser beam powers and reactant gas pressures. Nickel lines as small as 1 μm in width were written. From the growth kinetics, the vertical deposition rate of Nickel can be calculated. At low Ni(CO)4 pressures, typically below 0.3 mbar, deposition of flat-topped Nickel lines occurs. The deposition rate is proportional to the Ni(CO)4 pressure and independent of the laser-induced temperature. At reactant gas pressures above 0.3 mbar, Gaussian Nickel lines are obtained. The deposition rate is found to be independent of the Ni(CO)4 pressure and exhibits an activation energy of about 11.5 kcal mol-1. The measured electrical resistivity of the flat-topped lines is about 10 times higher than the bulk resistivity (7 μΩ·cm) while in the Gaussian regime this ratio falls below 1.5. The morphology and roughness of the deposited lines were investigated using both a scanning electron microscope (SEM) and an atomic force microscope (AFM). In the flat-topped regime, grains of about 100 nm are observed at the top of the Nickel lines while in the Gaussian regime the surface is smooth.

Bohumil Docekal - One of the best experts on this subject based on the ideXlab platform.

  • optimization of Nickel Tetracarbonyl generation and Nickel in situ trapping within a transversely heated graphite furnace for atomic absorption spectrometry
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2000
    Co-Authors: Bohumil Docekal, Petr Marek
    Abstract:

    Abstract The efficiency of Nickel Tetracarbonyl generation and of in situ trapping within a transversely heated graphite furnace was studied. The influence of experimental parameters of the flow injection generation system and in situ collection procedure for atomic absorption spectrometric determination of Nickel, i.e. pH of reaction mixture, concentration of sodium tetrahydroborate solution, reaction temperature, concentration of various electrolytes, several ‘heavy metal’ ions and hydride forming elements, trapping temperature, position of introduction capillary and carrier gas flow rates on the overall efficiency were investigated. The acidity of the reaction mixture and the kinetics of carbonyl formation are the limiting parameters of the whole generation procedure. The temperature of the tube, gas flow rate and the position of the capillary are the most critical parameters in trapping Nickel from Nickel Tetracarbonyl. Under optimum conditions, an overall efficiency of approximately 80% was found, evaluating atomic absorption spectrometric signals obtained by carbonyl generation/trapping procedure and by conventional liquid sampling procedure.

  • radiotracer investigation of Nickel Tetracarbonyl generation and Nickel in situ deposition within a graphite furnace
    Journal of Analytical Atomic Spectrometry, 2000
    Co-Authors: Bohumil Docekal, Petr Marek, Miloslav Vobecký
    Abstract:

    The efficiency of wet chemical generation of Nickel Tetracarbonyl and the efficiency of electrothermal trapping of Nickel from the volatile carbonyl within a longitudinally heated graphite furnace was studied separately by a radioactive indicator technique using the nuclides 56,57Ni. Generation and trapping efficiencies of up to 90 and 95%, respectively, were found. Consequently, an overall efficiency of about 80–90% could be achieved for the carbonyl generation in situ trapping electrothermal atomic absorption spectrometric method used in the determination of ultratrace amounts of Nickel. In addition to the acidity of the reaction mixture, the kinetics of the carbonylation plays a very important role in the generation of Nickel Tetracarbonyl. This phenomenon should be taken into account when designing a carbonyl generator. The interference of “heavy metal' ions, e.g. copper and zinc, seemed to be related to superimposed non-recognized processes taking place in the carbonylation reactor. Compromise conditions should be applied for effective trapping of Nickel introduced into the atomizer as the volatile carbonyl. The most important parameters are the temperature of the graphite tube, the total gas flow rate and the position of the introduction capillary. By performing radiographic experiments, Nickel was found to be deposited of a small area on the wall opposite the injection hole of the graphite tube. Very good agreement of results (within an uncertainty of 3% RSD) was obtained when evaluating overall efficiency from radioactive and complementary spectrometric data, demonstrating that the spectrometric approach is suitable for evaluating the overall efficiency.

Petr Marek - One of the best experts on this subject based on the ideXlab platform.

  • optimization of Nickel Tetracarbonyl generation and Nickel in situ trapping within a transversely heated graphite furnace for atomic absorption spectrometry
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2000
    Co-Authors: Bohumil Docekal, Petr Marek
    Abstract:

    Abstract The efficiency of Nickel Tetracarbonyl generation and of in situ trapping within a transversely heated graphite furnace was studied. The influence of experimental parameters of the flow injection generation system and in situ collection procedure for atomic absorption spectrometric determination of Nickel, i.e. pH of reaction mixture, concentration of sodium tetrahydroborate solution, reaction temperature, concentration of various electrolytes, several ‘heavy metal’ ions and hydride forming elements, trapping temperature, position of introduction capillary and carrier gas flow rates on the overall efficiency were investigated. The acidity of the reaction mixture and the kinetics of carbonyl formation are the limiting parameters of the whole generation procedure. The temperature of the tube, gas flow rate and the position of the capillary are the most critical parameters in trapping Nickel from Nickel Tetracarbonyl. Under optimum conditions, an overall efficiency of approximately 80% was found, evaluating atomic absorption spectrometric signals obtained by carbonyl generation/trapping procedure and by conventional liquid sampling procedure.

  • radiotracer investigation of Nickel Tetracarbonyl generation and Nickel in situ deposition within a graphite furnace
    Journal of Analytical Atomic Spectrometry, 2000
    Co-Authors: Bohumil Docekal, Petr Marek, Miloslav Vobecký
    Abstract:

    The efficiency of wet chemical generation of Nickel Tetracarbonyl and the efficiency of electrothermal trapping of Nickel from the volatile carbonyl within a longitudinally heated graphite furnace was studied separately by a radioactive indicator technique using the nuclides 56,57Ni. Generation and trapping efficiencies of up to 90 and 95%, respectively, were found. Consequently, an overall efficiency of about 80–90% could be achieved for the carbonyl generation in situ trapping electrothermal atomic absorption spectrometric method used in the determination of ultratrace amounts of Nickel. In addition to the acidity of the reaction mixture, the kinetics of the carbonylation plays a very important role in the generation of Nickel Tetracarbonyl. This phenomenon should be taken into account when designing a carbonyl generator. The interference of “heavy metal' ions, e.g. copper and zinc, seemed to be related to superimposed non-recognized processes taking place in the carbonylation reactor. Compromise conditions should be applied for effective trapping of Nickel introduced into the atomizer as the volatile carbonyl. The most important parameters are the temperature of the graphite tube, the total gas flow rate and the position of the introduction capillary. By performing radiographic experiments, Nickel was found to be deposited of a small area on the wall opposite the injection hole of the graphite tube. Very good agreement of results (within an uncertainty of 3% RSD) was obtained when evaluating overall efficiency from radioactive and complementary spectrometric data, demonstrating that the spectrometric approach is suitable for evaluating the overall efficiency.

Miloslav Vobecký - One of the best experts on this subject based on the ideXlab platform.

  • radiotracer investigation of Nickel Tetracarbonyl generation and Nickel in situ deposition within a graphite furnace
    Journal of Analytical Atomic Spectrometry, 2000
    Co-Authors: Bohumil Docekal, Petr Marek, Miloslav Vobecký
    Abstract:

    The efficiency of wet chemical generation of Nickel Tetracarbonyl and the efficiency of electrothermal trapping of Nickel from the volatile carbonyl within a longitudinally heated graphite furnace was studied separately by a radioactive indicator technique using the nuclides 56,57Ni. Generation and trapping efficiencies of up to 90 and 95%, respectively, were found. Consequently, an overall efficiency of about 80–90% could be achieved for the carbonyl generation in situ trapping electrothermal atomic absorption spectrometric method used in the determination of ultratrace amounts of Nickel. In addition to the acidity of the reaction mixture, the kinetics of the carbonylation plays a very important role in the generation of Nickel Tetracarbonyl. This phenomenon should be taken into account when designing a carbonyl generator. The interference of “heavy metal' ions, e.g. copper and zinc, seemed to be related to superimposed non-recognized processes taking place in the carbonylation reactor. Compromise conditions should be applied for effective trapping of Nickel introduced into the atomizer as the volatile carbonyl. The most important parameters are the temperature of the graphite tube, the total gas flow rate and the position of the introduction capillary. By performing radiographic experiments, Nickel was found to be deposited of a small area on the wall opposite the injection hole of the graphite tube. Very good agreement of results (within an uncertainty of 3% RSD) was obtained when evaluating overall efficiency from radioactive and complementary spectrometric data, demonstrating that the spectrometric approach is suitable for evaluating the overall efficiency.