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This article reports the valence-band x-ray photoelectron spectroscopy (XPS) of various forms of sodium phosphate. Valence-band spectra are compared to spectra generated from cluster and band-structure calculations. Five different forms of sodium phosphate are studied as follows, Na4P2O7, Na5P3O10, Na4P4O12, Na2H2P2O7, and NaH2PO2. Core-level XPS studies are of little use for differentiating between such similar compounds while valence band photoemission has been found to be particularly effective at identifying subtle differences in surface chemistry. The results indicate that the valence-band region clearly distinguishes between these different phosphates and that these differences can be predicted by spectra generated from both cluster and band-structure calculations.

Nanocomposite films were prepared by two methods in which lead sulfide (PbS) nanocrystals were contained in an organic matrix. One method used a wet chemical synthesis of the nanocrystals in the direct presence of a polymer, where the polymer controlled nanocrystal growth. The second method was gaseous deposition of nanocrystals into the organic phase. The two methods were similar in that the nanocrystals in the composites were free from surfactant capping layers that otherwise would add an interfacial region between the nanocrystal and the organic matrix. The gaseous deposition technique had several advantages over the wet chemical synthesis in that it allowed direct control over nanocrystal size and density, improved flexibility in the choice of organic phase, and was compatible with lithographic methods.

Valence band and core level X-ray photoelectron spectroscopy (XPS) were used to probe lead sulfide (PbS) nanoparticle–polymer nanocomposites. Composite materials were prepared by trapping commercially available monodisperse 3 and 10 nm PbS nanoparticles in two polymers, the non-conducting polymer, polystyrene, and the conjugated polymer, poly(2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene (referred to below as MEH-PPV). The nanocomposites prepared from commercial nanoparticles underwent oxidation, mainly to form lead sulfate. However, the narrow size distributions of the commercial nanoparticles allowed observation of distinct changes in the valence band from the 3 to 10 nm nanoparticles. Nanocomposites of 2–5 and 4–7 nm PbS nanoparticles were synthesized by growing the particles in poly(vinyl alcohol) (referred to below as PVA) and MEH-PPV, respectively. These composites both indicated the formation of lead sulfide nanoparticles. Furthermore, the XP spectra for the PVA/PbS composite displayed bonding between the PbS nanoparticles and the polymer while MEH-PPV showed no PbS–polymer bonding. The nanoparticles synthesized in MEH-PPV did not undergo oxidation. The particle size distributions of the synthesized nanoparticles were too broad to display size-dependent changes in the valence band.

This article continues a series of papers that shows how thin (10nm or less) oxide-free phosphate films can be formed on a number of metals. The films formed have potential as corrosion resistant films. Previous papers have shown that it is possible to extend the range of the surface coatings that can be formed by placing a thin polymer layer over the phosphate layer. In this work it is shown how the water insoluble polymer poly(ether ketone ketone) (PEKK) can be placed over a thin oxide-free phosphate film on aluminum metal. The surface and the interfaces involved were studied by valence band and core level x-ray photoelectron spectroscopy. Difference spectra in the valence band region were used to show that there is a chemical interaction between the PEKK and phosphate thin films on the aluminum metal. Three different phosphate film compositions were studied using different phosphorous containing acids, H3PO4, H3PO3, and H3PO2. This type of interaction illustrates the potential of phosphates to act as a...

This article reports the preparation of thin (less than 100A) oxide-free phosphate films of various compositions on vanadium metal. These films are interesting because of their potential for corrosion inhibition, adhesion promotion, and biocompatibility. Valence and core-level x-ray photoelectron spectroscopy (XPS) were used to characterize the films. The valence band spectra obtained were compared with spectra generated from band structure calculations for various vanadium phosphates and from previously reported spectra of vanadium phosphates. Vanadium phosphate coatings were created by the reaction of vanadium metal and different phosphorus-oxygen containing acids: H3PO4, H3PO3, H3PO2, and H2P2O7. This article focuses upon the valence band region which shows significant differences between the four vanadium phosphate films formed as well as clear differences between the these phosphates and vanadium oxides. The valence band spectra are effectively interpreted by band structure calculations.

The valence-band and core-level x-ray photoelectron spectroscopy (XPS) of vanadium phosphates are reported, and the valence-band spectra interpreted by various calculation models. The spectral interpretation of the vanadium phosphates is used to show that an oxide-free vanadium phosphate film corresponding to VO(H2PO4)2 can be prepared on vanadium metal. Three types of vanadium phosphate were investigated to provide an understanding of the XPS data for vanadium phosphates, and to demonstrate the differences between these phosphates and vanadium oxides. The three phosphates formed, VO(H2PO4)2, VOHPO4.0.5H2O, and VOPO4⋅2H2O were prepared by reaction of vanadium with phosphoric acid under a variety of conditions. The article focuses upon the valence-band region which shows significant differences between different types of vanadium phosphates as well as clear differences between the phosphates on the one hand and oxides on the other hand. The valence-band spectra are effectively interpreted by the multiple s...

The XPS spectra of vanadyl hydrogen phosphate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. The valence band region is determined by the features of the HPO42− ion which shows subtle but significant differences from the valence band region of the orthophosphate ion (PO43−). The valence band, survey, V 2p, V 3p, O 1s, P 2p, P 2s, and C 1s are reported.

We report the XPS spectra of sodium polyphosphate. XPS spectra were collected with a VSW HA150 x-ray photoelectron spectrometer using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of sodium polyphosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The features seen in the valence band are unique to the (P4O12)4− ion and therefore provide a means for distinguishing this compound from chemically similar compounds such as other phosphates. The valence band, survey, Na 1s, O 1s, C 1s, P 2s, P 2p, and Na 2s levels are reported.

We report the XPS spectra of sodium dihydrogenpyrophosphate. XPS spectra were collected with a VSW HA150 x-ray photoelectron spectrometer using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of sodium dihydrogenpyrophosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The features seen in the valence band are unique to the (H2P2O7)2− ion which shows small but significant differences from the (P2O7)4− ion. The valence band, survey, Na 1s, O 1s, C 1s, P 2s, P 2p, and Na 2s levels are reported.

We report the XPS spectra of sodium pyrophosphate. XPS spectra were collected with a VSW HA150 x-ray photoelectron spectrometer using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of sodium pyrophosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The features seen in the valence band are unique to the (P2O7)4− ion and therefore provide a means for distinguishing this compound from chemically similar compounds such as other phosphates. The valence band, survey, Na 1s, O 1s, C 1s, P 2s, P 2p, and Na 2s levels are reported.

The XPS spectra of vanadyl dihydrogenphosphate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. The valence band region is determined by the features of the HPO4− ion which shows subtle but significant differences from the valence band region of the orthophosphate ion (PO43−). The valence band, survey, V 2p, V 3p, O 1s, P 2p, P 2s, and C 1s are reported.

The XPS spectra of ferrous phosphate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of ferrous phosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The valence band, survey, and the P 2s, P 2p, Fe 2p, Fe 3p, O 1s, and C 1s core levels are reported.

We report the XPS spectra of sodium tripolyphosphate. XPS spectra were collected with a VSW HA150 x-ray photoelectron spectrometer using monochromatic Al Kα x-radiation. Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band of sodium tripolyphosphate due to the absence of interfering x-ray satellites from the intense O 2s region. The features seen in the valence band are unique to the (P3O10)5− ion and therefore provide a means for distinguishing this compound from chemically similar compounds such as other phosphates. The valence band, survey, Na 1s, O 1s, C 1s, P 2s, P 2p, and Na 2s levels are reported.

The XPS spectra of vanadyl orthophosphate dihydrate were collected with a VSW HA150 using monochromatic Al Kα x-radiation. The valence band region is determined by the features of the orthophosphate ion. The valence band region is typical of that of an orthophosphate compound.