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

Jale Hacaloglu - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of electrochemically synthesized p-toluene sulfonic acid doped polypyrrole by direct insertion probe pyrolysis mass spectrometry
    Journal of Analytical and Applied Pyrolysis, 2002
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    Abstract A direct insertion probe pyrolysis mass spectrometry technique was used to perForm a systematic thermal characterization of conducting polypyrrole doped with p -toluene sulfonic acid. The effect of dopant concentration on thermal stability and degradation products was investigated using undoped and dedoped polypyrrole samples. The data indicate that polymerization of pyrrole in the absence of dopant produces an Aromatic structure, which transForms into the quinoid Form at high dopant concentrations. Reduction, namely dedoping, yielded a decrease in the intensity of PTS based peaks and transFormation from quinoid Form to Aromatic Form. Intense toluene, SO 2 , and H 2 S peaks recorded at high temperatures indicated the decomposition of the dopant. This trend, decomposition at high temperatures instead of evaporation at low or moderate temperatures was associated with a strong (probably chemical) interaction between the dopant and the host polymer.

  • Thermal and structural characterization of polypyrrole by direct-insertion probe pyrolysis mass spectrometry
    Synthetic Metals, 2001
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    There have been extensive studies on structural characterization of conducting polypyrrole, PPY using various techniques. The two proposed structures are the Aromatic Form corresponding to the undoped state and the quinoid Form corresponding to the doped state. However, actual structure appears to be more complicated and the relationship between the dopant used and the structure was not totally clarified. In this study direct insertion probe pyrolysis mass spectrometry technique was applied to monitor thermal decomposition products of polypyrrole which may further be used for structural elucidation. Three different dopants namely, p-toluene sulfonate, tetrafluoroborate and dodecyl sulfate were used in the synthesis of polypyrrole to investigate the effect of dopant on thermal stability and structure.

Miklos Kertesz - One of the best experts on this subject based on the ideXlab platform.

  • Raman spectra and ground state of the new low bandgap polymer poly(thienopyrazine)
    Synthetic Metals, 1995
    Co-Authors: Johann Kastner, Hans Kuzmany, Daniel Végh, M. Landl, Lilee Cuff, Miklos Kertesz
    Abstract:

    Abstract Raman modes of the new processable polymer poly(2,3-alkyl-thieno[3,4-b]-pyrazine) with a bandgap of about 0.9 eV were measured and calculated. Raman spectroscopy revealed two strong lines at about 1520 cm −1 and 1560 cm −1 in the CC stretching mode region. By changing the exciting laser line these modes exhibit a dispersion of 16 and 25 cm −1 /eV, respectively. Calculations on the ground state revealed that the quinonoid structure is by about 13 kcal/mol per repeat unit more stable than the Aromatic Form. By using the scaled quantum mechanical oligomer force field method we calculated the Raman spectrum of the quinonoid Form and identified the mode at 1520 cm −1 as the inter-ring A g vibration.

  • Raman Spectra of Poly(2,3-R,R-thieno[3,4-b]pyrazine). A New Low-Band-Gap Polymer
    Macromolecules, 1995
    Co-Authors: Johann Kastner, Hans Kuzmany, Daniel Végh, M. Landl, Lilee Cuff, Miklos Kertesz
    Abstract:

    Vibrational modes of the new processable polymer poly(2,3-R,R-thieno[3,4-b]pyrazine) with a band gap of about 0.9 eV were measured by resonance Raman scattering and calculated by a quantum chemical method. Raman spectroscopy of the pristine polymer revealed a strong line at about 1520 cm -1 and doublet structure at around 1560 cm -1 in the C=C stretching region. By changing the exciting laser line these lines exhibit a dispersion which is about 16 cm -1 /eV for the line at 1520 cm -1 . Substitution at the 2,3-positions with alkyl groups has only a weak influence on the vibrational properties. Several modes shift moderately toward lower frequencies with increasing chain length. The utilization of thiophene rings as substituents results in a much more efficient mode softening. In addition, the Raman response of FeCl 3 -doped samples is presented. Changes in relative intensities and weak line shifts were observed. Calculations on the ground state revealed that the quinonoid structure is by about 13 kcal/ mol per repeat unit more stable than the Aromatic Form. By using the scaled quantum mechanical oligomer force field (SQMOFF) method the Raman spectrum of the quinonoid Form was calculated. According to this the lines observed experimentally in the C=C stretching mode region originate from the inter-ring A g vibration and from an A g mode which mainly comprises intra-ring stretches superposed with a B 2g mode. The vibrational results are consistent with the calculated quinonoid ground-state geometry

  • Raman spectra of the new low bandgap polymer poly(2,3-substituted thieno [3,4-b]-pyrazine)
    International Conference on Science and Technology of Synthetic Metals, 1994
    Co-Authors: Johann Kastner, Miklos Kertesz, Daniel Végh, Lilee Cuff, Hans Kuzmany
    Abstract:

    Summary Form only given. Vibrational modes of a new processable polymer with a bandgap as low as 0.95 eV have been measured by resonance Raman scattering and calculated by a quantum chemical method. Raman spectroscopy of the pristine polymer revealed two strong lines at about 1520 cm/sup -1/ and 1563 cm/sup -1/ in the C=C stretching mode region. By changing the exciting laser line these modes exhibit a dispersion of 14 and 25 cm/sup -1//eV, respectively. Substitution at the 2,3-positicns with alkyl groups has only a weak influence on the vibrational properties. The mode at 1520 cm/sup -1/ shifts moderately towards lower frequencies with increasing chain length. However, the utilization of thiophene rings as substituents results in a much higher mode softening. In addition, the Raman response of FeCl/sub 3/-doped samples is presented. A change in relative intensities and different line shifts were observed. In order to determine the structure of the ground state Raman spectra were calculated for the quinonoid and Aromatic Form and compared with the experimental data. It turned cut that the two strong lines experimentally observed originate from an interring vibration and from a mode which mainly comes from the thiopbene rings along the polymeric backbone.

Tamer Uyar - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of electrochemically synthesized p-toluene sulfonic acid doped polypyrrole by direct insertion probe pyrolysis mass spectrometry
    Journal of Analytical and Applied Pyrolysis, 2002
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    Abstract A direct insertion probe pyrolysis mass spectrometry technique was used to perForm a systematic thermal characterization of conducting polypyrrole doped with p -toluene sulfonic acid. The effect of dopant concentration on thermal stability and degradation products was investigated using undoped and dedoped polypyrrole samples. The data indicate that polymerization of pyrrole in the absence of dopant produces an Aromatic structure, which transForms into the quinoid Form at high dopant concentrations. Reduction, namely dedoping, yielded a decrease in the intensity of PTS based peaks and transFormation from quinoid Form to Aromatic Form. Intense toluene, SO 2 , and H 2 S peaks recorded at high temperatures indicated the decomposition of the dopant. This trend, decomposition at high temperatures instead of evaporation at low or moderate temperatures was associated with a strong (probably chemical) interaction between the dopant and the host polymer.

  • Thermal and structural characterization of polypyrrole by direct-insertion probe pyrolysis mass spectrometry
    Synthetic Metals, 2001
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    There have been extensive studies on structural characterization of conducting polypyrrole, PPY using various techniques. The two proposed structures are the Aromatic Form corresponding to the undoped state and the quinoid Form corresponding to the doped state. However, actual structure appears to be more complicated and the relationship between the dopant used and the structure was not totally clarified. In this study direct insertion probe pyrolysis mass spectrometry technique was applied to monitor thermal decomposition products of polypyrrole which may further be used for structural elucidation. Three different dopants namely, p-toluene sulfonate, tetrafluoroborate and dodecyl sulfate were used in the synthesis of polypyrrole to investigate the effect of dopant on thermal stability and structure.

Johann Kastner - One of the best experts on this subject based on the ideXlab platform.

  • Raman spectra and ground state of the new low bandgap polymer poly(thienopyrazine)
    Synthetic Metals, 1995
    Co-Authors: Johann Kastner, Hans Kuzmany, Daniel Végh, M. Landl, Lilee Cuff, Miklos Kertesz
    Abstract:

    Abstract Raman modes of the new processable polymer poly(2,3-alkyl-thieno[3,4-b]-pyrazine) with a bandgap of about 0.9 eV were measured and calculated. Raman spectroscopy revealed two strong lines at about 1520 cm −1 and 1560 cm −1 in the CC stretching mode region. By changing the exciting laser line these modes exhibit a dispersion of 16 and 25 cm −1 /eV, respectively. Calculations on the ground state revealed that the quinonoid structure is by about 13 kcal/mol per repeat unit more stable than the Aromatic Form. By using the scaled quantum mechanical oligomer force field method we calculated the Raman spectrum of the quinonoid Form and identified the mode at 1520 cm −1 as the inter-ring A g vibration.

  • Raman Spectra of Poly(2,3-R,R-thieno[3,4-b]pyrazine). A New Low-Band-Gap Polymer
    Macromolecules, 1995
    Co-Authors: Johann Kastner, Hans Kuzmany, Daniel Végh, M. Landl, Lilee Cuff, Miklos Kertesz
    Abstract:

    Vibrational modes of the new processable polymer poly(2,3-R,R-thieno[3,4-b]pyrazine) with a band gap of about 0.9 eV were measured by resonance Raman scattering and calculated by a quantum chemical method. Raman spectroscopy of the pristine polymer revealed a strong line at about 1520 cm -1 and doublet structure at around 1560 cm -1 in the C=C stretching region. By changing the exciting laser line these lines exhibit a dispersion which is about 16 cm -1 /eV for the line at 1520 cm -1 . Substitution at the 2,3-positions with alkyl groups has only a weak influence on the vibrational properties. Several modes shift moderately toward lower frequencies with increasing chain length. The utilization of thiophene rings as substituents results in a much more efficient mode softening. In addition, the Raman response of FeCl 3 -doped samples is presented. Changes in relative intensities and weak line shifts were observed. Calculations on the ground state revealed that the quinonoid structure is by about 13 kcal/ mol per repeat unit more stable than the Aromatic Form. By using the scaled quantum mechanical oligomer force field (SQMOFF) method the Raman spectrum of the quinonoid Form was calculated. According to this the lines observed experimentally in the C=C stretching mode region originate from the inter-ring A g vibration and from an A g mode which mainly comprises intra-ring stretches superposed with a B 2g mode. The vibrational results are consistent with the calculated quinonoid ground-state geometry

  • Raman spectra of the new low bandgap polymer poly(2,3-substituted thieno [3,4-b]-pyrazine)
    International Conference on Science and Technology of Synthetic Metals, 1994
    Co-Authors: Johann Kastner, Miklos Kertesz, Daniel Végh, Lilee Cuff, Hans Kuzmany
    Abstract:

    Summary Form only given. Vibrational modes of a new processable polymer with a bandgap as low as 0.95 eV have been measured by resonance Raman scattering and calculated by a quantum chemical method. Raman spectroscopy of the pristine polymer revealed two strong lines at about 1520 cm/sup -1/ and 1563 cm/sup -1/ in the C=C stretching mode region. By changing the exciting laser line these modes exhibit a dispersion of 14 and 25 cm/sup -1//eV, respectively. Substitution at the 2,3-positicns with alkyl groups has only a weak influence on the vibrational properties. The mode at 1520 cm/sup -1/ shifts moderately towards lower frequencies with increasing chain length. However, the utilization of thiophene rings as substituents results in a much higher mode softening. In addition, the Raman response of FeCl/sub 3/-doped samples is presented. A change in relative intensities and different line shifts were observed. In order to determine the structure of the ground state Raman spectra were calculated for the quinonoid and Aromatic Form and compared with the experimental data. It turned cut that the two strong lines experimentally observed originate from an interring vibration and from a mode which mainly comes from the thiopbene rings along the polymeric backbone.

Levent Toppare - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of electrochemically synthesized p-toluene sulfonic acid doped polypyrrole by direct insertion probe pyrolysis mass spectrometry
    Journal of Analytical and Applied Pyrolysis, 2002
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    Abstract A direct insertion probe pyrolysis mass spectrometry technique was used to perForm a systematic thermal characterization of conducting polypyrrole doped with p -toluene sulfonic acid. The effect of dopant concentration on thermal stability and degradation products was investigated using undoped and dedoped polypyrrole samples. The data indicate that polymerization of pyrrole in the absence of dopant produces an Aromatic structure, which transForms into the quinoid Form at high dopant concentrations. Reduction, namely dedoping, yielded a decrease in the intensity of PTS based peaks and transFormation from quinoid Form to Aromatic Form. Intense toluene, SO 2 , and H 2 S peaks recorded at high temperatures indicated the decomposition of the dopant. This trend, decomposition at high temperatures instead of evaporation at low or moderate temperatures was associated with a strong (probably chemical) interaction between the dopant and the host polymer.

  • Thermal and structural characterization of polypyrrole by direct-insertion probe pyrolysis mass spectrometry
    Synthetic Metals, 2001
    Co-Authors: Tamer Uyar, Levent Toppare, Jale Hacaloglu
    Abstract:

    There have been extensive studies on structural characterization of conducting polypyrrole, PPY using various techniques. The two proposed structures are the Aromatic Form corresponding to the undoped state and the quinoid Form corresponding to the doped state. However, actual structure appears to be more complicated and the relationship between the dopant used and the structure was not totally clarified. In this study direct insertion probe pyrolysis mass spectrometry technique was applied to monitor thermal decomposition products of polypyrrole which may further be used for structural elucidation. Three different dopants namely, p-toluene sulfonate, tetrafluoroborate and dodecyl sulfate were used in the synthesis of polypyrrole to investigate the effect of dopant on thermal stability and structure.