X-ray photoelectron spectroscopy (XPS) has been used for the quantitative and qualitative analysis method in the development of functional material because of its high surface sensitivity. To determine the thickness of the thin film using XPS, the attenuation length (AL) of the photoelectron is an important parameter. For a long time, inelastic mean free path (IMFP) has been used as an alternative of AL because the values of IMFP can be calculate using the equation TPP2M [1]. However the effect of the elastic scattering is not considered in the evaluation of IMFPs. Recently effective attenuation length (EAL) is proposed [2]. I have been studied the EAL of the photoelectron in the SiO2 thin films with the energy range of 100–1000 eV [3] at old BL-13C station [4,5]. In this P-type proposal, the preliminary experiments for the measurements of EALs of the photoelectrons in the silicon oxide thin film with lower energy.

An Al thin film deposited on a Si(111) substrate in an ultrahigh vacuum (UHV) chamber was oxidized by oxygen exposure of 4 and 100 L at room temperature. Then, X-ray photoelectron spectroscopy (XPS) using X-rays with various excitation energies using synchrotron radiation (SR) was carried out to evaluate the thickness of the very thin oxide. The obtained spectra showed Al 2p peaks assigned to the metal and the oxide. From their peak ratios obtained by the curve fitting of the spectra, the depth profile of oxygen composition was derived by considering the analysis depth of XPS on the basis of the effective attenuation length (EAL) of photoelectrons. By simulation using a single-layer model, the thicknesses of the oxide generated by oxygen exposure of 4 and 100 L were determined. The results suggest that the oxide layer generated by only a few langumuir of oxygen in the initial stage suppresses the diffusion of oxygen to the interface of the oxide and the metal.

Al2O3 films (2–5nm) deposited on SiO2/Si (100) n-type substrate with thickness 500μm were characterized by Synchrotron Radiation- X-ray Photoelectron Spectroscopy (SR-XPS). Excitation energy 730eV show surface sensitive results compare to 1000eV. Using excitation energy 730eV, Al, Si, O core-level elements and their excited species were analyzed. Plasmon loss peak with energy separation (18.8–19.1eV) for Al2p main peak and (14.7–15.3eV) for Al2s main peak is likely due to bulk plasmon. XPS spectra of O1s peak showed different onset and energy seperation for each sample. Energy seperation between O1s peak and onset of plasmon is 8.4eV for 5nm lead to band gap of Al2O3 layer. But and in case of 2nm this value is 9.2eV, hence, it is likely corresponds to SiO2 interfacial layer.The reason for this might consider as top Al2O3 form island rather than homogenous oxide layer.

Effective attenuation lengths (EALs) of the photoelectrons in SiO2 were measured at various energies by photoelectron spectroscopy of the SiO2 thin film on the Si substrate with a certified thickness using synchrotron radiation (SR) as an excitation source. On the basis of the experimentally determined EALs, the thickness of another thin film was estimated and compared to that determined with the x-ray reflectivity (XRR) method.

A series of hydrodesulfurization (HDS) catalysts was prepared by impregnation of Co and Mo on sol-gel B-Al2O3 Supports with B/Al ratios of 0, 0.02,0.04,0.08,0.20,0.32,0.49, and 0.61. The thiophene HDS and dibenzothiophene (DBT) HDS activities were both maximal for the catalyst with B/Al = 0.04, with respective values 70 and 42% higher than those for an industrial reference catalyst. These maxima in HDS activity correlated with the previously reported presence of isolated BO4 surface species. These BO4 Species were responsible for a local maximum in the acidity of the B-Al2O3 supports when B/Al = 0.04. In contrast, the formation of mixed oxides (A(9)B(2) and A(2)B) or B2O3 that also resulted in enhanced acidity of the B-Al2O3 supports had a detrimental effect on the HDS activity.The 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS activity over the CoMo/B-Al2O3 catalysts decreased when the B/Al ratio was increased. This was attributed to the strong direct desulfurization character of the CoMo catalysts supported on the B-Al2O3 supports, because high hydrogenation ability toward the C=C double bonds is essential prior to sulfur removal from 4,6-DMDBT. The excellent performance in the thiophene and DBT HDS of the CoMo/B-Al2O3 catalysts is particularly useful for ultra-deep HDS of light fractions. (c) 2006 Published by Elsevier B.V.

th periodic table and L3-edge for Pt and Au in standard solutions (1000 ppm standards for Atomic Absorption Spectrometry by Wako Pure Chemical Industries, Ltd.) in transmission mode were measured at Photon Factory using precise quartz cells with 0.5, 1 and 2 cm thickness which are certified by Japan Quality Assurance Organization using the three-dimensional measurement system (Carl Zeiss UMM550) traceable to national standard of Iodine-stabilized He-Ne laser (NMIJ). The error was below 3 µm in 4 points on optical windows at 293 K.

The local structures around Mo supported on USY zeolites containing different amounts of extra-framework Al species (EFAL) were investigated to elucidate the effects of EFAL on the location and dispersion of Mo sulfide catalysts. Mo K-edge EXAFS analysis indicated that Mo sulfide catalysts were highly dispersed and located, at least in part, in the micropores of USY zeolites, independent of the EFAL amounts. The dispersion of Mo sulfide was found to decrease with increasing amount of EFAL in the zeolites. EXAFS analysis of Mo oxide catalysts, the precursor of the sulfide catalysts, suggested that Mo oxide catalysts deposited on EFAL during the catalyst preparation were reluctant to disperse into micropores and formed larger MoS2 clusters during sulfiding that lowered the dispersion.

In-situ XAFS observation of Pd-Pt catalysts supported on SiO2, Al2O3 and USY was carried out during reduction and sulfidation processes. Under sulfidation conditions, Pd-Pt species on USY was the most seriously sulfided, whereas, no contribution of sulfur was observed in Pt LIII-edge EXAFS of sulfided Pd-Pt/SiO2. Pd-Pt species on Al2O3 showed intermediate properties for sulfidation. It is found that Pd and Pt metal species formed relatively uniform alloy particles on SiO2 and Al2O3, whereas, on USY, Pd and Pt atoms were segregated in the alloy particles.

A preliminary investigation of photon-stimulated ion desorption (PSID) from condensed deuterated formamide (HCOND2) by using polarization-angle-dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with velocity-selected time-of-flight (TOF) mass spectrometry, is presented. It was found that the PSID yield of total D+ ion is enhanced by the N 1s→σ*(ND) transition at both grazing and normal photon incidence angles and its enhanced yield shows no polarization dependence despite of direct PSID, which indicates the ND bonds are not aligned with the surface-oriented CNO molecular plane of HCOND2. It was also found that the fastest velocity components of H+ and D+ ions monotonically decrease as the energy at the normal incidence angle. This finding suggests that X-ray-induced electron stimulated desorption (XESD) via secondary electrons resulting from valence photoelectrons; indirect PSID is a dominant process in the fastest components.

Preparation of catalysts in molten salt has great possibilities for producing excellent catalysts because the reaction in molten salt is quite different from that in water. MoO3 dissolves in molten salt and finally becomes molybdate via intermediate oxoanions as catalytic active species. The structure of the oxoanions and the mechanism of stabilization on zirconia in the preparation process remain unknown. In the previous study, we have clarified the changes in the composition of molybdate species during the catalyst preparation procedures by quenching the samples. In the present paper, the structure of Mo oxoanions in molten nitrates at different temperatures was investigated by in situ XAFS.Samples were prepared from MoO3 in molten nitrate (NaNO3). The mixture was heated up to various temperatures from 298 to 773 K. The in situ XAFS spectra of the molted samples were measured on Mo K-edge using an in situ cell at the BL-10B in the Photon Factory.The EXAFS was analyzed quantitatively to obtain the structure and composition of Mo oxoanions in the molten nitrates by multi-component fitting based on a linear combination of chi(k) of reference samples and simulation using FEFF8 code in consideration of the Debye-Waller factor. The results show a change of composition of oxoanions in molten nitrate during the reaction.

A series of CoMo/Al2O3 catalysts was prepared by impregnation on a series of alumina powders synthesized by the sol–gel method with different hydrolysis ratios R (defined as [H2O]/[aluminum-tri-sec-butoxide (ASB)]; R=3,4,…,12,13). The oxide precursors were characterized and subsequently tested in the hydrodesulfurization (HDS) of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Mainly due to their large pore diameters of ca. 6nm, the catalysts prepared from the alumina with hydrolysis ratio R=7–10 showed higher HDS activity compared with the activities of the other prepared catalysts. The effect of the pore diffusional limitation was more significant than expected, due to the ink-bottle shape of the pores of the prepared catalysts with hydrolysis ratio R<8 and R>10. Due to highly dispersed CoMo active phase, the HDS activity of the prepared catalysts with hydrolysis ratio R=8 and 9 for thiophene was similar to that of a reference industrial catalyst that was designed and manufactured for deep HDS of diesel fuel fractions. Furthermore, the HDS activity of the prepared catalysts with hydrolysis ratio R>5 for DBT was higher than that of the reference industrial catalyst. For 4,6-DMDBT, however, the reference industrial catalyst showed higher HDS activity compared with the activities of the prepared catalysts. Relatively high HDS activity was observed for the prepared catalysts with R=9 and 10 with cylindrical pore shape and with a high proportion of strong acid sites. The strong acidity supposedly enhanced the hydrogenation activity of the catalysts that was essential for the HDS of 4,6-DMDBT.

Structural changes of pyromellitimido-oxydianiline (PMDA-ODA) polyimide (PI) films by UV irradiation were studied by means of XAFS and XPS. UV irradiation in air was found to cause oxidative cleavage of the imide ring of the PMDA part, whereas that in vacuum changed the conjugated structure involving nitrogen but did not likely open the imide ring. The results indicate that the combined analysis of XAFS and XPS is a powerful tool for polymer surfaces.

In the course of the development of a new fine‐pitch four‐point probe, surface oxide layers of the probe material were characterized by a non‐destructive depth profiling analysis with a variable excitation XPS using synchrotron radiation. The high surface sensitivity of this technique has allowed us to measure the ultra‐thin thickness of the oxide layer on the probe material without damage. The XPS of W 4f of the tungsten metal was measured in the excitation x‐ray energy range 100–1200 eV at the Photon Factory (BL‐13C), Tsukuba, Japan and analysed by the simulation of attenuation in the layer models using the values of inelastic mean free path (IMFP) and effective attenuation length (EAL) calculated by the National Institute of Standards and Technology (NIST) database programs 71 and 82, respectively. The values of practical EAL at 1 nm depth were smaller than the IMFP by 20–40% and resulted in a smaller thickness of the surface oxide layer than for that of IMFP by about 20%. The result showed that the thickness of the surface oxide layer of the tungsten metal was 1.0 nm ‘as received’ and 0.5 nm after polish. The XPS of W 4f of the superfine grain (grain size < 0.5 µm) tungsten carbide–cobalt wires with 0.45 mm diameter, which is a probe size of conventional four‐point probes, were measured and the results indicated that the thickness of the surface oxide layer of the tungsten carbide–cobalt was 0.4 nm ‘as received’, and the thickness of the oxide layer was increased to 0.5 nm after polish. The XPS of W 4f of the tungsten carbide–cobalt wire with 0.05 mm diameter of an actual probe for a new fine‐pitch four‐point probe system was also measured and the results indicated that the thickness of the surface oxide layer was 0.6 nm. The XPS of W 4f also indicated the existence of an intermediate thin layer of WO2 between W and WO3. Copyright © 2004 John Wiley & Sons, Ltd.

The effects of Si/Al ratio of starting NaY zeolites on structural changes during ion exchange treatments were studied. Three zeolites of different Si/Al ratio were subjected to three cycles of ion exchange treatment using (NH4)2SO4 and subsequent calcinations, and analyzed after each cycle. In the first ion exchange, the structural changes of the zeolites were almost independent of the Si/Al ratio of the starting NaY zeolites. For all three zeolites, about 60% of Na ions were exchanged, and the relative crystallinity decreased to about 80% of the starting NaY. In the second and third ion exchanges, the structural changes depended on the Si/Al ratio of the starting NaY zeolites. The zeolitic framework of Y zeolite with a low Si/Al ratio of 2.4 deteriorated, whereas Y zeolite with a medium Si/Al ratio of 2.8 and Y zeolite with a high Si/Al ratio of 4.1 retained their high crystallinity even after the third ion exchange. Furthermore, among the three zeolites, Y zeolite with a medium Si/Al ratio of 2.8 showed largest degrees of ion exchange, dealumination, and mesopore formation.

Introduction Since hard coatings such as tetrahedral amorphous carbon (ta:C) are of growing interest for protecting surfaces of industrial machines and high capacity tools against wear and friction or for biomedical applications more information about the structure-to-property relation is required. Therefore core level photo emission and other spectral features in the x-ray photoelectron spectra (XPS) of carbon materials were used to derive “fingerprints” for selected carbon species. Besides the surface properties which can be gained by constant-energy XPS, information of different surface regions is required to receive information on the chemical structure of the material in different depths to understand the deposition process. Non-destructive depth profiling is possible by using photoelectron spectroscopy exploiting the variation of excitation energy to get information from several monolayers in depth down to the minimum of monolayer resolution. This is possible because there is a correlation of the effective attenuation length (EAL) of electrons in a solid with their kinetic energy [1]. A variation of the energy of the exciting X-ray radiation provides the possibility to adjust the kinetic energy of the photoelectrons as well as the EAL. The minimum EAL of C 1s photoelectrons should occur at roughly 350 eV Xray photon energy.

USY (Ultra Stable Y-type Zeolite) supported Pd-Pt catalysts (Pd-Pt/USY) are efficient for deep dearomatization of diesel fuel, and they show higher activity than monometallic Pd catalysts. The in-situ XAFS (X-ray absorption Fine Structure) technique was applied to structural analysis of Pd and Pd-Pt particles supported on USY to elucidate the effect of Pt. During reduction, monometallic Pd and Pt particles gathered to form a Pd-Pt alloy particle. Upon exposure to H2S Pt atoms were almost completely sulfided, whereas, some part of the Pd atoms remained as metallic particles. It is concluded that Pt atoms were localized on the surface of metal particles in Pd-Pt/USY.

Partial-ion-yield (PIY) spectra using ion time-of-flight (TOF) method and near-edge absorption fine structure (NEXAFS) spectra were measured for 2-(perfluorooctyl)ethanethiol [CF3(CF2)7(CH2)2SH] self-assembled monolayer (F8-SAM) on Au(111) near carbon K-edge. The PIY spectra of the F8-SAM at the magic angle, where –CF3 groups exist at the surface were compared with those of the rubbed polytetrafluoroethylene (PTFE) thin film. The F+ intensity from the F8-SAM at the photon energy of the sharp peak of the NEXAFS, which originates from the excitation of C1s electron to σ*(C–F) states at –CF2– chain, was extremely smaller than that from the rubbed PTFE film. This result clearly indicates that the ions observed by PIY do not originate from the film inside but from the surface. This was confirmed by changes in ion-TOF mass spectra during soft X-ray induced etching of the F8-SAM. The NEXAFS peaks of the F8-SAM were also assigned by considering PIY results.

The structural and acidic properties of sol–gel prepared alumina powders as catalyst supports were modified by adjusting the hydrolysis ratio, R (i.e. molar ratio of water relative to the alumina precursor, R=[H2O]/[aluminium-tri-sec-butoxide (ASB)]). Structural properties (e.g. porosity) and acidic properties were measured for alumina powders prepared with various R values, from 3 to 13. For R<9 and R>10, first-order particles were closely packed with ink-bottle-type pore structures, whereas for R=9 or 10, first-order particles were loosely packed with a spatial fractal arrangement that yielded pseudo-cylindrical pore structures. In addition, the alumina powders prepared with R=9 or 10 had larger water pore volume and stronger acidity than those with other R values. These properties unique to the powders prepared with R=9 or 10 were ascribed to relatively short Al–O–Al chain lengths that resulted in loose packing of first-order particles. The results here indicate that alumina powders with favorable properties as catalyst supports (e.g. mean pore diameter) can be tailored by selecting the appropriate R in the sol–gel synthesis process.