Hi Jean Michel, Thanks for your interest in this discussion. Unfortunately, I have not used the synchrotron for XPS and am not familiar with tricks of this technique. However, as a rough idea, since the energy of the photons you have used in synchrotron (350 eV) are almost close to the binding energy of π–π* transition (≈ 291 eV) it might has not been energetic enough to excite a visible signal. What if you use a higher energy photon?
Hi Jean Michel, Thanks for your interest in this discussion. Unfortunately, I have not used the synchrotron for XPS and am not familiar with tricks of this technique. However, as a rough idea, since the energy of the photons you have used in synchrotron (350 eV) are almost close to the binding energy of π–π* transition (≈ 291 eV) it might has not been energetic enough to excite a visible signal. What if you use a higher energy photon?
Hi Dmitry, Thanks for your interest in this question. My general intuition after all discussions interchanged, has been that a precise and quantitative conclusion about the electrical conductivity of carbon, is not possible just based on the π–π* transition component of C 1s XPS spectra, or at least, based on the current knowledge and investigations. Maybe a dedicated work, could cast some more light on the quantitative capacities of this technique for this particular characteristic (electrical conductivity) of carbon. For the time being, we could at most, say that there is a qualitative relation, where more conductive forms of carbon (like CNTs based on my personal research) show a clear π–π* transition and less conductive forms of carbon (like activated carbon or graphene oxide) do not show that, or show a very weak transition.
Hi Dmitry, Thanks for your interest in this question. My general intuition after all discussions interchanged, has been that a precise and quantitative conclusion about the electrical conductivity of carbon, is not possible just based on the π–π* transition component of C 1s XPS spectra, or at least, based on the current knowledge and investigations. Maybe a dedicated work, could cast some more light on the quantitative capacities of this technique for this particular characteristic (electrical conductivity) of carbon. For the time being, we could at most, say that there is a qualitative relation, where more conductive forms of carbon (like CNTs based on my personal research) show a clear π–π* transition and less conductive forms of carbon (like activated carbon or graphene oxide) do not show that, or show a very weak transition.
Dear Mazdak Hashempour The fact that at each node in the CNT is one pi-electron. And the conductivity is determined not by their number and width of the conduction band. A conduction band width depends on the parameter describing the electron hopping from site to site. This option increases the conduction band. A Coulomb repulsion prevents jumping. And the conduction band is divided into two subzones. The distance between them: HOMO-LUMO is the difference between the Coulomb repulsion U parameter at one site and the band width W. The number of pi-electrons may be increased or decrease only by adding to the system of chemical elements having an excess or deficiency of electrons.
Dear Mazdak Hashempour The fact that at each node in the CNT is one pi-electron. And the conductivity is determined not by their number and width of the conduction band. A conduction band width depends on the parameter describing the electron hopping from site to site. This option increases the conduction band. A Coulomb repulsion prevents jumping. And the conduction band is divided into two subzones. The distance between them: HOMO-LUMO is the difference between the Coulomb repulsion U parameter at one site and the band width W. The number of pi-electrons may be increased or decrease only by adding to the system of chemical elements having an excess or deficiency of electrons.
Yes and no... Yes, you will detect the presence of pi-bonds, which are needed for conduction of electrons, but that will mainly tell you that it is not an insulator (as with sp3 in diamond). The electrical conductivity of a metal or semimetal is dominated by the crystallinity. So defects, or mechanical strain, that you don't see in XPS or NEXAFS will still influence and may well dominate the electrical conductivity.
Yes and no... Yes, you will detect the presence of pi-bonds, which are needed for conduction of electrons, but that will mainly tell you that it is not an insulator (as with sp3 in diamond). The electrical conductivity of a metal or semimetal is dominated by the crystallinity. So defects, or mechanical strain, that you don't see in XPS or NEXAFS will still influence and may well dominate the electrical conductivity.
I struggled with this for a while. I needed solid references to explain the pi-pi* transitions and its relation to electrically conductive carbons. Here are the DOI's 10.1016/S0169-4332(03)00550-6 10.1021/la052922r 10.1016/j.carbon.2004.03.005
I struggled with this for a while. I needed solid references to explain the pi-pi* transitions and its relation to electrically conductive carbons. Here are the DOI's 10.1016/S0169-4332(03)00550-6 10.1021/la052922r 10.1016/j.carbon.2004.03.005
Hi Mazdak, from a more detailed analysis of the carbon edge you can get even more informations than the presence of Pi orbital, and as Kristen correctly said, this is no measure of electrical conductivity. For example CNT can be metallic or semiconducting depending on chirality, but are both characterized by the presence of Pi bonds. For example, consider that the Pi orbital are always perpendicular to the C-C sigma bond. With an angle resolved XPS you can get the direction of a CNT material (macroscopic geometry and even the so called chirality if they are pure enough) and this will tell in which direction they conduct and possibly even if they are metallic or semiconducting CNT. See for example: Chem. Mater., 2006, 18 (23), pp 5624–5629
Hi Mazdak, from a more detailed analysis of the carbon edge you can get even more informations than the presence of Pi orbital, and as Kristen correctly said, this is no measure of electrical conductivity. For example CNT can be metallic or semiconducting depending on chirality, but are both characterized by the presence of Pi bonds. For example, consider that the Pi orbital are always perpendicular to the C-C sigma bond. With an angle resolved XPS you can get the direction of a CNT material (macroscopic geometry and even the so called chirality if they are pure enough) and this will tell in which direction they conduct and possibly even if they are metallic or semiconducting CNT. See for example: Chem. Mater., 2006, 18 (23), pp 5624–5629
Hi Mazdak, Thanks for answer. If we use higher energies (100 eV for example), we see clearly the transition on the C1s spectrum at 292 eV. So this trasition depends on the energy of photoelectrons. Regards
Hi Mazdak, Thanks for answer. If we use higher energies (100 eV for example), we see clearly the transition on the C1s spectrum at 292 eV. So this trasition depends on the energy of photoelectrons. Regards
Dear Mazdak, I am interested in the π–π* transition component of the C 1s. XPS spectrum I observed that in graphene material, the shake up is well visible with ESCA Lab machine. However using photons of 350 eV in the synchrotron, the satellite is not visible on graphene. Is this explainable by differnt probabilities ? Thnks
Dear Mazdak, I am interested in the π–π* transition component of the C 1s. XPS spectrum I observed that in graphene material, the shake up is well visible with ESCA Lab machine. However using photons of 350 eV in the synchrotron, the satellite is not visible on graphene. Is this explainable by differnt probabilities ? Thnks
Hello everyone, I have XPS data fro Ni and got some peaks at 774.56 eV, 901.63 eV, 47.64eV. i could not find what transition occurs at these peaks. if anyone know about this, please tell me
Hello everyone, I have XPS data fro Ni and got some peaks at 774.56 eV, 901.63 eV, 47.64eV. i could not find what transition occurs at these peaks. if anyone know about this, please tell me
Hi Mazdak,
Thank you!
Hi Mazdak,
Thank you!
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VOTE
Hi Jean Michel,
Thanks for your interest in this discussion. Unfortunately, I have not used the synchrotron for XPS and am not familiar with tricks of this technique. However, as a rough idea, since the energy of the photons you have used in synchrotron (350 eV) are almost close to the binding energy of π–π* transition (≈ 291 eV) it might has not been energetic enough to excite a visible signal. What if you use a higher energy photon?
Hi Jean Michel,
Thanks for your interest in this discussion. Unfortunately, I have not used the synchrotron for XPS and am not familiar with tricks of this technique. However, as a rough idea, since the energy of the photons you have used in synchrotron (350 eV) are almost close to the binding energy of π–π* transition (≈ 291 eV) it might has not been energetic enough to excite a visible signal. What if you use a higher energy photon?
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VOTE
Right, so it makes sense.
Right, so it makes sense.
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VOTE
Hi Dmitry,
Thanks for your interest in this question. My general intuition after all discussions interchanged, has been that a precise and quantitative conclusion about the electrical conductivity of carbon, is not possible just based on the π–π* transition component of C 1s XPS spectra, or at least, based on the current knowledge and investigations. Maybe a dedicated work, could cast some more light on the quantitative capacities of this technique for this particular characteristic (electrical conductivity) of carbon. For the time being, we could at most, say that there is a qualitative relation, where more conductive forms of carbon (like CNTs based on my personal research) show a clear π–π* transition and less conductive forms of carbon (like activated carbon or graphene oxide) do not show that, or show a very weak transition.
Hi Dmitry,
Thanks for your interest in this question. My general intuition after all discussions interchanged, has been that a precise and quantitative conclusion about the electrical conductivity of carbon, is not possible just based on the π–π* transition component of C 1s XPS spectra, or at least, based on the current knowledge and investigations. Maybe a dedicated work, could cast some more light on the quantitative capacities of this technique for this particular characteristic (electrical conductivity) of carbon. For the time being, we could at most, say that there is a qualitative relation, where more conductive forms of carbon (like CNTs based on my personal research) show a clear π–π* transition and less conductive forms of carbon (like activated carbon or graphene oxide) do not show that, or show a very weak transition.
More
VOTE
Dear Mazdak Hashempour
The fact that at each node in the CNT is one pi-electron. And the conductivity is determined not by their number and width of the conduction band. A conduction band width depends on the parameter describing the electron hopping from site to site. This option increases the conduction band. A Coulomb repulsion prevents jumping. And the conduction band is divided into two subzones. The distance between them: HOMO-LUMO is the difference between the Coulomb repulsion U parameter at one site and the band width W.
The number of pi-electrons may be increased or decrease only by adding to the system of chemical elements having an excess or deficiency of electrons.
Dear Mazdak Hashempour
The fact that at each node in the CNT is one pi-electron. And the conductivity is determined not by their number and width of the conduction band. A conduction band width depends on the parameter describing the electron hopping from site to site. This option increases the conduction band. A Coulomb repulsion prevents jumping. And the conduction band is divided into two subzones. The distance between them: HOMO-LUMO is the difference between the Coulomb repulsion U parameter at one site and the band width W.
The number of pi-electrons may be increased or decrease only by adding to the system of chemical elements having an excess or deficiency of electrons.
More
VOTE
Yes and no...
Yes, you will detect the presence of pi-bonds, which are needed for conduction of electrons, but that will mainly tell you that it is not an insulator (as with sp3 in diamond).
The electrical conductivity of a metal or semimetal is dominated by the crystallinity. So defects, or mechanical strain, that you don't see in XPS or NEXAFS will still influence and may well dominate the electrical conductivity.
Yes and no...
Yes, you will detect the presence of pi-bonds, which are needed for conduction of electrons, but that will mainly tell you that it is not an insulator (as with sp3 in diamond).
The electrical conductivity of a metal or semimetal is dominated by the crystallinity. So defects, or mechanical strain, that you don't see in XPS or NEXAFS will still influence and may well dominate the electrical conductivity.
More
VOTE
Hello Mazdak,
Have you found answer on this question? I'm curious because I have the same question right now.
Regards,
Dmitry
Hello Mazdak,
Have you found answer on this question? I'm curious because I have the same question right now.
Regards,
Dmitry
More
VOTE
I struggled with this for a while. I needed solid references to explain the pi-pi* transitions and its relation to electrically conductive carbons.
Here are the DOI's
10.1016/S0169-4332(03)00550-6
10.1021/la052922r
10.1016/j.carbon.2004.03.005
I struggled with this for a while. I needed solid references to explain the pi-pi* transitions and its relation to electrically conductive carbons.
Here are the DOI's
10.1016/S0169-4332(03)00550-6
10.1021/la052922r
10.1016/j.carbon.2004.03.005
More
VOTE
Hi Mazdak,
from a more detailed analysis of the carbon edge you can get even more informations than the presence of Pi orbital, and as Kristen correctly said, this is no measure of electrical conductivity. For example CNT can be metallic or semiconducting depending on chirality, but are both characterized by the presence of Pi bonds.
For example, consider that the Pi orbital are always perpendicular to the C-C sigma bond. With an angle resolved XPS you can get the direction of a CNT material (macroscopic geometry and even the so called chirality if they are pure enough) and this will tell in which direction they conduct and possibly even if they are metallic or semiconducting CNT. See for example: Chem. Mater., 2006, 18 (23), pp 5624–5629
Hi Mazdak,
from a more detailed analysis of the carbon edge you can get even more informations than the presence of Pi orbital, and as Kristen correctly said, this is no measure of electrical conductivity. For example CNT can be metallic or semiconducting depending on chirality, but are both characterized by the presence of Pi bonds.
For example, consider that the Pi orbital are always perpendicular to the C-C sigma bond. With an angle resolved XPS you can get the direction of a CNT material (macroscopic geometry and even the so called chirality if they are pure enough) and this will tell in which direction they conduct and possibly even if they are metallic or semiconducting CNT. See for example: Chem. Mater., 2006, 18 (23), pp 5624–5629
More
VOTE
Hi Mazdak,
Thanks for answer.
If we use higher energies (100 eV for example), we see clearly the transition on the C1s spectrum at 292 eV. So this trasition depends on the energy of photoelectrons. Regards
Hi Mazdak,
Thanks for answer.
If we use higher energies (100 eV for example), we see clearly the transition on the C1s spectrum at 292 eV. So this trasition depends on the energy of photoelectrons. Regards
More
VOTE
Dear Mazdak,
I am interested in the π–π* transition component of the C 1s. XPS spectrum I observed that in graphene material, the shake up is well visible with ESCA Lab machine. However using photons of 350 eV in the synchrotron, the satellite is not visible on graphene. Is this explainable by differnt probabilities ?
Thnks
Dear Mazdak,
I am interested in the π–π* transition component of the C 1s. XPS spectrum I observed that in graphene material, the shake up is well visible with ESCA Lab machine. However using photons of 350 eV in the synchrotron, the satellite is not visible on graphene. Is this explainable by differnt probabilities ?
Thnks
More
VOTE
Hello everyone, I have XPS data fro Ni and got some peaks at 774.56 eV, 901.63 eV, 47.64eV. i could not find what transition occurs at these peaks. if anyone know about this, please tell me
Hello everyone, I have XPS data fro Ni and got some peaks at 774.56 eV, 901.63 eV, 47.64eV. i could not find what transition occurs at these peaks. if anyone know about this, please tell me
More
VOTE