摘要:

Du Pont E-120 high modulus pitch-based carbon fiber was potentiostatically oxidized in (NH4)2CO3solution and analyzed with both core level and valence band XPS. Compared to the untreated E-120 fiber, this electrochemically oxidized fiber had a much higher oxygen content on its surface. Nitrogen was also found on this carbon fiber sample after the treatment in (NH4)2CO3solution, but no nitrogen was found either before or after the treatment in HNO3solution. Our previously reported work [see Y. Xie and P. M. A. Sherwood, Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–αcalculations with model compounds. In this work, the valence band spectrum shows that there were three different types of oxygen-containing functional groups formed on the fiber surface when the fiber was electrochemically oxidized in (NH4)2CO3solution, but only one type of oxygen-containing functionality formed after the electrochemical treatment in HNO3solution. We also reported [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.46, 1158 (1991)] that the reproducibility of the potentiostatic treatment was not as good as that of the galvanostatic treatment, although the results from potentiostatic oxidation and galvanostatic oxidation were very similar.

ISSN:1055-5269    

DOI:10.1116/1.1247646

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Both core level and valence band XPS spectra were obtained from a Union Carbide highly oriented pyrolytic graphite (HOPG) monochromator sample. Compared to Du Pont and Amoco pitch-based carbon fibers with different modulus and some PAN-based carbon fibers, the HOPG had much less oxygen components on the surface than the carbon fibers, except Du Pont E-120 high modulus pitch-based carbon fiber. [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.43, 1153 (1989); Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992).] No nitrogen was found on the HOPG surface, nor on any of the pitch-based carbon fibers measured in our laboratory, but nitrogen was shown in all the PAN-based carbon fibers. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–αcalculations with model compounds. Although both HOPG and E-120 samples had little oxygen on their surfaces (with E-120 even less), the valence band spectra of these two samples showed that the oxygen species in the HOPG surface and E-120 fiber surface were different because the separations between the O 2speak and the C 2speak in the two spectra are different.

ISSN:1055-5269    

DOI:10.1116/1.1247647

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Du Pont E-120 high modulus pitch based carbon fiber was potentiostatically oxidized in HNO3solution and analyzed with both core level and valence band XPS. Compared to the untreated E-120 fiber, the potentiostatically oxidized fiber had a much higher oxygen content on its surface. Both surface and bulk graphitic structures were severely disordered by the electrochemical treatment as evidenced by both XPS and XRD studies. [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.43, 1153 (1989); Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992).] However, no nitrogen was found on this pitch-based carbon fiber either before or after the treatment in HNO3solution. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra, and could be well interpreted by X–αcalculations with model compounds. In this work, the valence band spectrum, together with the O 1score level spectrum, showed that there was only one single-type oxygen-containing functional group formed on the fiber surface when the fiber was electrochemically oxidized in HNO3solution. We also reported [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.44, 1621 (1990)] that the highly oxidized carbon fiber surface functionality would gradually decompose after exposure to the x rays inside the XPS spectrometer, and that [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.45, 1158 (1991)] the reproducibility of the potentiostatic treatment was not as good as that of the galvanostatic treatment, although the results from potentiostatic oxidation and galvanostatic oxidation were about the same.

ISSN:1055-5269    

DOI:10.1116/1.1247648

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Du Pont E-120 high modulus pitch-based carbon fiber was galvanostatically oxidized in HNO3solution and analyzed with both core level and valence band XPS. Compared to the untreated E-120 fiber, the galvanostatically oxidized fiber had a much higher oxygen content on its surface. Both surface and bulk graphitic structures were severely disordered by the electrochemical treatment as evidenced by both XPS and XRD studies. [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.43, 1153 (1989); Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621, (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645, (1992).] However, no nitrogen was found on this pitch-based carbon fiber either before or after the treatment in HNO3solution. Our previously reported work [Y. Xie and P. M. A Sherwood, Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–αcalculations with model compounds. In this work, the valence band spectrum, together with the O 1score level spectrum, showed that there was only one single-type oxygen containing functional group formed on the surface when the fiber was electrochemically oxidized in HNO3solution. We also reported [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.45, 1158 (1991)] that the reproducibility of the galvanostatic treatment was better than that of the potentiostatic treatment, although the galvanostatic oxidation gave a very similar result to that of the potentiostatic oxidation.

ISSN:1055-5269    

DOI:10.1116/1.1247649

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Du Pont E-120 high modulus pitch-based carbon fiber was galvanostatically oxidized in (NH4)2CO3solution and analyzed with both core level and valence band XPS. Compared to the untreated E-120 fiber, the galvanostatically oxidized fiber had a very much higher oxygen content on its surface. Nitrogen was also found on this carbon fiber sample after the treatment in (NH4)2CO3solution but no nitrogen was found either before or after the treatment in HNO3solution. Our previously reported work [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.43, 1153 (1989); Chem. Mater.1, 427 (1989);2, 293 (1990); Appl. Spectrosc.44, 797 (1990); Chem. Mater.3, 164 (1991); Appl. Spectrosc.44, 1621 (1990);45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood,ibid.46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–αcalculations with model compounds. In this work, the valence band spectrum shows that there were three different types of oxygen-containing functional groups formed on the fiber surface when the fiber was electrochemically oxidized in (NH4)2CO3solution but only one type of oxygen-containing functionality formed after the electrochemical treatment in HNO3solution. We also reported [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc.45, 1158 (1991)] that the reproducibility of the galvanostatic treatment was better than that of the potentiostatic treatment, although the results from potentiostatic oxidation and galvanostatic oxidation were very similar.

ISSN:1055-5269    

DOI:10.1116/1.1247650

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A commercial LiF powder sample was investigated using x-ray photoelectron spectroscopy. Sample preparation included washing in acetone and methanol, pressing into indium foil and gold decoration for charge correction. Measured binding energies were very similar to those previously reported. [See W. E. Morgan, J. R. Van Wazer, and W. J. Stec, J. Amer. Chem. Soc.95, 751 (1973); K. Hamrin, G. Johansson, U. Gelius, C. Nordling, and K. Siegbahn, Phys. Scr.1, 277 (1970); C. D. Wagner, W. M. Riggs, L. E. Davis, J. F. Moulder, and G. E. Muilenberg,Handbook of X-ray Photoelectron Spectroscopy(Physics Electronics Division, Perkin Elmer, Eden Prarie, MN, 1979).] Because F is commonly used as a reference element for tabulated sensitivity factors, data in this paper are useful in evaluating empirical relative sensitivity factors for a specific instrument, in this instance, a Perkin Elmer-Physical Electronics Model 5400 XPS.

ISSN:1055-5269    

DOI:10.1116/1.1247651

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Auger electron spectra of the cubic phase of boron nitride are presented. The line shapes of the boron and nitrogenKLLtransitions are characteristic for this phase of boron nitride. Therefore, cubic-boron nitride can be distinguished from other phases of boron nitride based on Auger line shapes. The powder specimen was prepared for analysis by burnishing onto a silver substrate. A single grain of boron nitride was analyzed.

ISSN:1055-5269    

DOI:10.1116/1.1247652

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Auger electron spectra of the hexagonal phase of boron nitride are presented. The line shapes of the boron and nitrogenKLLtransitions are characteristic for this phase of boron nitride. Therefore, hexagonal-boron nitride can be distinguished from other phases of boron nitride based on Auger line shapes. The powder specimen was prepared by burnishing onto an indium substrate.

ISSN:1055-5269    

DOI:10.1116/1.1247653

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A crystal of infrared-grade potassium bromide (KBr) was cleaved in air using a clean single-edged razor blade. The crystal was adhered to double-sided adhesive tape and analyzed by XPS at an angle that maximizes the information associated with subsurface bulk. The crystal's dimensions were 3 mm × 3 mm × 10 mm (w×h×l), and only the freshly exposed surface was analyzed. A mesh made of nickel wire was placed about 1 mm above the surface of the sample to flatten the electric fields on the sample.

ISSN:1055-5269    

DOI:10.1116/1.1247654

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A first derivative CKLLAuger electron spectrum from an Fe film which was heated to react with adventitious surface hydrocarbons is presented as a “finger print” for the identification of an iron–carbon reaction. The iron carbide peak shape is significantly different from that of the adventitious hydrocarbons prior to heating the sample and a subsequent 1 min argon ion sputter at 1 keV or that of bulk graphite [K. M. Geib, C. W. Wilmsen, J. E. Mahan, and M. C. Bost, J. Appl. Phys.61, 5299 (1987)]. The carbon is probably bonded as Fe3C because this compound is thermodynamically more stable than the other iron carbides and because the carbon is in an iron rich environment.

ISSN:1055-5269    

DOI:10.1116/1.1247655

出版商:American Vacuum Society    

年代:1992

数据来源: AIP