Graphite intercalation compounds are characterized by ionic carbon-fluorine bonding. Also, the peaks for carbons attached to a single fluorine atom, two fluorine atoms, and carbons attached to fluorines have characteristic binding energies. As a quantitative method, it gives the relative ratios of detectable elements on the surface of the material. Additional analysis can be done to further elucidate the surface structure. Hybridization, bonding, functionalities, and reaction progress are among the characteristics that can be inferred using XPS.
The application of XPS to carbon nanomaterials provides much information about the material, particularly the first few atomic layers, which are most important for the properties and uses of carbon nanomaterials. Data Collection X-ray photoelectron XP spectra provide the relative frequencies of binding energies of electrons detected, measured in electron-volts eV.
Kuznetsov, Rice University. Limitations Both hydrogen and helium cannot be detected using XPS. XPS for Carbon Nanomaterials Despite the aforementioned limitations, XPS is a powerful surface technique that can be used to accurately detect the presence and relative quantities of elements in a sample.
Sample Preparation Carbon nanomaterials present certain issues in regard to sample preparation. Analysis and Applications for Carbon Nanomaterials Chemical Speciation The XP survey scan is an effective way to determine the identity of elements present on the surface of a material, as well as the approximate relative ratios of the elements detected.
Adapted from F. Xie, W. Xie, J. Chen, X. Liu, D. Lu, and W. Zhang, J. B , , 26 , Adapted with permission from C. Yang, H. Kanoh, K. Kaneko, M. Yudasaka, and S. Iijima, J. B , , , Copyright: American Chemical Society Bonding and Functional Groups XP spectra give evidence of functionalization and can provide insight into the identity of the functional groups.
Adapted with permission from F. Liang, J. Beach, P. Rai, W. Guo, R. Hauge, M. Pasquali, R. Smalley, and W. Billups, Chem. Further Characterization High resolution scans of each of the element peaks of interest can be obtained to give more information about the material.
Hybridization The hybridization of carbons influences the properties of a carbon nanomaterial and has implications in its structure. Adapted from P. Merel, M.
Tabbal, M. Chaker, S. Moisa, and J. Margot, Appl. Reaction Completion Comparing the relative intensities of various C1s peaks can be powerful in verifying that a reaction has occurred.
Adapted with permission from E. Dillon, C. Crouse, and A. Wang, W. Hoffmann, M. Lu, and J. X-ray beam induces photo-ejection of an electron from left hydrogen and right helium. The Science For the first time, and contrary to popular belief, scientists measured the vibrational structure of hydrogen and helium atoms by X-rays.
The Impact The results disprove the misconception that it's impossible to obtain X-ray photoelectron spectroscopy XPS spectra of hydrogen and helium, the two lightest elements of the Periodic Table. Summary X-ray photoelectron spectroscopy XPS is one of the most powerful techniques in materials science. A lower energy, high flux X-ray source increases the cross-section for H and He dramatically, and ambient pressure apparatus are needed to handle these gas phase elements.
Note that lab based AP-XPS cannot detect these elements - the synchrotron source is essential for this type of work. Reference: [1] J. Zhong, M. Wang, W. Hoffmann, M. Lu, J. Boscoboinik, Appl.
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