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Tribological properties and surface characteristics of ethylene–propylene-diene elastomers were studied as a function of carbon black (CB) content. The surface analysis was performed inside and outside the wear track by X-ray photoelectron spectroscopy (XPS) in order to evaluate possible compositional changes produced by rubbing. Carbon black content had only a small influence on the surface chemistry of the unworn surfaces. However, on the surfaces subjected to friction, the oxygen concentration decreased with increasing CB content. Neither the surface analysis by XPS nor the wettability tests revealed important thermal degradation of the polymer in these friction tests.

A surface study of electrodeposited cerium oxide based coatings is presented. Different surface analytical techniques were used in order to obtain complementary information to fully characterize such complex systems. X-ray Photoelectron Spectroscopy was used as the main technique to determine the surface composition of the coating. The analysis of the core level peaks of the elements provides additional information about the functional groups present on the surface. A mixture of Ce (III) and Ce (IV) was found in the coating and their proportion was calculated at different depths. The analysis of the O 1s core level peak revealed a triple structure whose origin will be discussed. To support the results obtained, electron stimulated desorption was performed. The study was completed with Auger electron spectroscopy and Raman spectroscopy, both techniques having different surface sensitivities. From all these results, it is derived that incomplete electrochemical reactions occurred during the growth of the coatings. This led to rather complex compositions, in which defective cerium oxides are the major species. In addition, hydroxides, carbonates and nitrates are also present, together with adsorbed water.

6 pages., A study of the tribodesorption of hydrogen stimulated by the friction of an alumina pin on stainless steel in ultrahigh vacuum at room temperature is presented. A special two-chamber ultrahigh-vacuum system separated by a well-defined orifice of low conductance is used to determine minute amounts of desorbed gases. The friction cell allows the control of the normal force of the alumina pin on the stainless-steel surface, the frequency of sweeping, as well as the dwell, i.e., the time between consecutive strokes. The profile of the p(H2)-t desorption curve shows a near-exponential increase in pressure to a stable value; then, after the friction cessation, the pressure decreases back to the initial value. The desorption curve presents an oscillating signal over the continuous one that corresponds with the sweeping frequency. An important aspect of the present research has been to elucidate the origin of the desorbed hydrogen: bulk or surface of materials. In this respect, the amount of tribodesorbed hydrogen is compared with the amount of adsorbed hydrogen at dwell times from 0.5 to 4 s. This adsorption is 50 and 5 times lower than the desorbed hydrogen at normal forces of 0.072 and 0.218 N, respectively, and a dwell time of 4 s. An important finding is that the amount of desorbed hydrogen is irrespective of the dwell time, and the desorption rate increases linearly with sweeping frequency. The authors conclude that the origin of the desorbed hydrogen is in the bulk.

A study of the calibration of leaks by comparison with reference standard leaks calibrated at a National Metrology Laboratory is presented. The simplicity and efficiency of the method make it suitable for calibrations of leaks carried out at the industrial level. A commercial leak tester equipped with a mass spectrometer tuned to helium is used for the comparison. The main origins of uncertainties and their contributions to the expanded uncertainty are presented. In particular, discussion is devoted to the long-term stability, shift, or depletion of the reference standard leaks and the resulting impact on the expanded uncertainty. Results of application of the procedure for calibration of a leak of similar metrological characteristics to the reference standard leaks are also presented.

Cr, CrN, TiCr coatings have been investigated as potential anti-multipactor coatings. The coatings were synthesized by cathodic-arc reactive evaporation in Ar–N 2 atmosphere where the ion energy is controlled by substrate biasing. Chemical state analysis and surface composition were studied by X-ray photoemission spectroscopy (XPS), whereas bulk composition and depth profile were studied by glow discharge optical emission spectroscopy (GDOES). The surface morphology was studied by optical profilometry (OP) and scanning electron microscopy (SEM). The compositions of the coatings were CrN and Ti 40 Cr 60 and they were homogeneous in depth. Surface oxidation was higher in Ti 40 Cr 60 than in CrN. Coatings deposited at high negative bias show lower deposition rate and had lower surface roughness than those obtained at low bias. Secondary electron emission yield (SEY) was higher for CrN than for Ti 40 Cr 60 , both before and after low-energy Ar + ion bombardment. The SEY of Ti 40 Cr 60 (1.17 maximum) was clearly smaller than the others. The maximum yield, σ m , and the first crossover electron energy, E 1 , are the most important parameters, and ( E 1 / σ m ) 1/2 is a good figure of merit. This quantity was approximately 3 eV 1/2 for Cr and CrN and 4 eV 1/2 for Ti 40 Cr. After Ar + ion bombardment, the average value improved significantly to 8.9 eV 1/2 for Cr and CrN and 10.2 eV 1/2 for Ti 40 Cr 60 . The radio-frequency multipactor performance of these materials was simulated using the experimentally determined SEY parameters.

The aim of the present work was to study the morphological, structural, and chemical analysis as a function of depth in vanadium alloys with a 5 at.% of titanium implanted at 673 K with 1.2 keV N+ ions, by transmission electron microscopy (TEM), glow discharge (GD) analysis, and x-ray photoemission spectroscopy. These results are correlated with those of previously published nanoindentation tests, and the species and chemical states responsible for the increase in hardness are identified. The maximum increase in hardness corresponds to the highest N concentration, measured by both photoemission spectroscopy and GD. In addition, the thickness of the layer (≈1000 nm), where structural modifications are observed using TEM, can also be directly correlated with the thickness of the implanted layer, where an incremental increase in hardness has previously been measured. These findings support the conclusion that the formation of vanadium and titanium nitride/oxynitrides (–N–O,–O–N–H) compounds are responsible for the increased hardness of these V–5at.% Ti samples implanted with N at low ion energy and high sample temperature.

The present work describes a preliminary study of friction-induced surface reactions in ultra-high vacuum of H and D atoms adsorbed on stainless steel. Deuterium has been implanted in the sample by electrolysis of D2O. A pin with a ball end under controlled load produces the friction in alternating passes across the surface. A sample manipulator controls the normal and tangential loads of the pin on the surface. The spectra of the total pressure and ion current of H 2 + as a function of friction time at different sweeping speeds are presented. Electron-stimulated desorption (ESD) has been used to verify the positive implantation of D atoms into the sample. The friction experiments on D-doped samples show that the reaction of the H and D surface atoms is to desorb as H2 and HD, i.e. second-order desorption. ESD also shows the presence of F and O species on the surface.

The reactivity of D2 16O and H2 18O with thin films of MgO(1 0 0) at room temperature was studied by electron stimulated desorption time of flight (ESDTOF) mass spectrometry. The MgO(1 0 0) thin films were grown on Si(1 0 0) at 1000 K by RF sputtering in an Ar (90%) and O (10%) atmosphere. The energy of the incident electrons ranged from 5 to 600 eV and the incident electron current on the sample was 100 nA. When the surface is exposed to D2O, the peaks of the ESDTOF surface ion spectra correspond to H+, D+, O+ and OD+ desorbed ions. After H2 18O exposure, H+, 16O+, and 18O+ desorbed ions are observed. Both 16O+ and 18O+ ions have a bimodal structure, which corresponds to oxygen ions with most probable kinetic energies of 5.3±0.5 and 9.0±0.9 eV. This bimodal structure is strongly affected by the energy of the incident electrons as well as by the adsorbed species. At electron energies lower than 250 eV the state with the lowest kinetic energy almost disappears. The two peaks at 5.3±0.5 and 9.0±0.9 eV of the bimodal structure are consistent with those observed in previous studies on bulk MgO(1 0 0) at 6.0±0.6 and 9.0±0.9 eV energies. The ion yields of desorbed ions for thin films and bulk samples are dramatically different. These results are discussed with respect to the surface reactive adsorption sites as well as to the secondary electron yield.

The dynamical characteristics of a vacuum system in respect of pressure are critical for studying the dynamical desorption processes such as those produced by mechanically stimulated desorption in vacuum. In the present work, a mathematical model of the instant pressure in a vacuum system has been developed assuming an intermittent square-wave desorbed gas flow. In this case, the duration of the pressure transient is proposed to be used as a generalized criterion of the rate of the desorbed gas flow and, consequently, of the instant pressure behaviour. The dependences of the transient duration on the pumping speed, system volume, molar mass of the desorbed gas as well as on the period and the on–off ratio of the desorption process have been revealed. The developed model made no assumptions on the physical nature of the gas source, i.e. desorption, leaking, etc., and can be used for different applications.

The ion-induced desorption yield from pure aluminium, oxygen free high conductivity copper (OFHC) and films of copper electrodeposited on stainless steel, has been studied for unbaked samples and samples after 24 h of baking at 80, 120, 150 and 200 °C. Measurements were performed using argon ions of energy 3 keV and current density 2.5(×10 -8 )-10 -6 A cm -2 . The desorption is focused on those gases usually present in ultrahigh vacuum systems, such as H 2 , CO, CO 2 , CH 4 and C x H y . The ion-induced desorption yields are presented as a function of the ion dose to the sample surface and are discussed according to the surface material and surface treatment. The lowest ion yields of 6.5 and 6.8 molecules per ion, respectively, are obtained for Al and Cu samples after a bake-out of the system at 200 °C.

This paper describes the modifications introduced by nitrogen implantation on V5 at.% Ti alloys at high energy. Two sets of samples were treated with three successive atomic and molecular nitrogen implantations, in order to obtain flat profiles of nitrogen concentration, namely 20 and 40%. On implanted samples microhardness tests with a final load of 2 mN showed a hardness increase by a factor of 2. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to identify the concentrations and chemical states of the elements present in the high dose implanted V5Ti surface. The obtained results indicate a correlation between the hardness increase and the nitrogen implantation. From the spectroscopic results we can distinguish three different regions: an amorphous carbon layer up to 10 nm from the surface, followed by an interface of mixed amorphous carbon and carbide (VC–TiC) of approximately 20 nm, in which nitrogen is in the form of nitride. The third region from 30 nm is characterized by a decrease in the oxygen concentration of 40%, together with slight nitrides increase and stable carbides.

The aim of the present work is to elucidate the role played by lithium impurities in the D 2 O adsorption on MgO(1 0 0) surfaces at room temperature and on H and D diffusion processes by using electron stimulated desorption (ESD). The growth of the D 2 O layer has been studied by recording the intensity of O + , OD + and D + desorbed ions. Whereas for undoped MgO surfaces the O + intensity decreases with coverage, in Li-doped MgO surfaces the intensity increases. These findings together with the observed threshold energy of D + desorbed ions at 55±5 eV indicate that adsorbed D 2 O undergoes preferentially total dissociation on the MgO : Li system. This threshold energy corresponds to the Mg 2p excitation, which means that the D species are bonded to the Mg atoms.

Processes of adsorption–desorption with glycine admitted to the TiO2(110)(1×2) reconstructed surface have been studied using synchrotron light, energy 55 eV, and with coverages both sub to monolayer, and multilayer at room temperature. The findings are discussed in terms of processes of dissociative adsorption at the sub-monolayer stage with only minor amounts of the amino radical of the glycine molecule remaining at the surface. The Ti 3d) peak is significantly affected in the evolution towards initial monolayer coverage. Aspects of photon induced desorption with photoelectron spectroscopy are compared with thermal treatments of the glycine-covered surface.

The main characteristics of an ultrahigh vacuum system for absolute pressure calibration in the range from 130 kPa to 0.1 Pa are presented. Calibration can be performed either in dynamic or static equilibrium. The ultimate pressure is in the region of 10 -6 Pa, after exposing the system to atmospheric pressure without baking and after a few hours of pumping. The outgassing rate and pumpdown characteristics of the system following its exposure to atmospheric pressure are presented. The main metrological characteristics of the system as well as the optimum measuring uncertainty are given. A calibration of a Pirani gauge and a budget of the associated uncertainties are also presented.

Photon damage of multilayers of glycine adsorbed on a TiO 2 (110) surface at room temperature has been studied with photoelectron spectroscopy of the valence band, the 2s band, and the Ti 3p level using synchrotron radiation at the Daresbury S.R.S. The UPS spectra of the multilayer (comprising about seven monolayers) show structures which can be assigned to the molecular structure of the zwitterionic form of glycine. Photon induced damage of multilayers up to θ =2 monolayers produces a first order desorption of the zwitterionic molecules with total cross section 5.4×10 −16 cm 2 which is similar to the ionisation cross section in the gas phase. The remaining layer is formed by C, NH x ( x =1,2) and OH hydroxyl species. A significant feature is the increase of the structure at 0.8 eV pointing to the growth of Ti 3+ surface species. This could be due to the formation of OH radicals on the surface or the adsorption of fragments on top of the O surface atoms involving some charge transfer to the surface.

Outgassing of SS surfaces under sliding friction in ultra-high vacuum has been studied by ad-desorption mass-spectrometry and Auger electron spectroscopy. Experiments have been performed at normal loads of the indent in the range from 0.02 up to 0.87N, sweeping frequencies from 48 to 124 min-1 and linear sliding speed 7.5 mm/s. The P–t outgassing curve presents an oscillating current over a continuous one and three well different parts: (i) an initial desorption peak of high intensity, (ii) a region of nearly stable pressure and (iii) a decreasing of the pressure when friction is stopped. The outgassing rate slowly decreases with the number of sweeps. The AES analysis shows that the chemical composition and rugosity of the rubbed area of surface depends on the friction conditions. For loads from 0 to 72 mN, no chemical changes in the surface composition are observed, while for loads up to 870 mN, the concentration of Fe increases and concentration of Cr decreases depending on the friction duration. The outgassing process is a combination of gas diffusing process from the outermost layers and desorption from the surface.

The fluorine contamination on MgO(100) surfaces is studied using Electron Stimulated Desorption (ESD) and Auger Electron Spectroscopy (AES). While Ar+ ion sputtering is very effective to clean the carbon contamination on the surface, the fluorine content does not significantly decrease. Thermal treatments of the sample considerably increase the F surface concentration due to its diffusion from the bulk to the surface. Heating the sample at 700 K simultaneously with H2O exposure produces a decrease in the fluorine signal. The ion kinetic energy distribution of the F+ ion shows two peaks at 2.4 and 5 eV. The threshold energy of the F+ ion desorption is at 60 eV.

The influence of the ion implantation of 1×10 15 ions/cm 2 of silicon and 1×10 14 ions/cm 2 of cerium at 150 keV on the oxidation behaviour of a 0.80%Cr–0.40%Mo heat-resistant 13CrMo 44 ferritic steel was studied at 973 K in air for 144 h under isothermal conditions. The implanted surfaces and the corrosion products formed on the surface were characterized by means of AES, SEM and XRD. Theoretical calculations were performed by TRIM96 computational code. From the present study it was concluded that silicon enhances selective oxidation of chromium and a more protective oxide scale was found to grow. However, cerium confers a detrimental effect by cracking and spalling of the oxide layers formed at high temperature.

The influence of implanted silicon, molybdenum and cerium on the oxidation behaviour of a 18Cr8Ni stainless steel was studied at 1173 K up to 144 h in air under isothermal conditions in order to verify the enhanced selective oxidation of chromium by these elements. The implanted surface and the corrosion products formed were characterized by means of AES, SEM, EDS and XRD. Implanted depth profiles were calculated by TRIM96 computational code. The implanted silicon and cerium markedly improved protection against oxidation of the alloy by enhanced chromium transport while molybdenum gave rise to an accelerated oxidation due to the formation of volatile MoO 3 species. Further, ion implantation was found to play a beneficial effect against decarburization of the alloy.

An electron-stimulated desorption (ESD) study of electron damage of a D2O layer adsorbed on the MgO(100) surface at room temperature is presented. After exposing the surface to D2O, the surface spectrum shows the main ESD component to be D+ ions, with lower intensity signals corresponding to O+ and OD+ ions. When the surface is simultaneously exposed to heavy water and electron bombardment, there is a rapid initial increase of the D+ intensity accompanied by a decrease of the intensity of the O+ ions. Electron damage of the surface after exposing to D2O produces a significant decrease of the D+ intensity, while the O+ and OD+ intensities decrease more slowly. Heavy water adsorption does not change the form of the ion kinetic energy distribution of the O+ ions with electron dose, except for a decrease in intensity. Electron damage increases the intensity of the ion kinetic energy distribution of D+ again without changing its shape. These experiments show that heavy water adsorption under electron bombardment does not induce any chemistry of the adsorbed species, but enhances the fragmentation rate of the OD species which, in turn, increases the yield of D+ ions. Values of total desorption cross-sections for the three ions species are reported.

The adsorption of SO2 on TiO2(110) surfaces at 100 K has been studied by means of the X-ray photoemission and ultra-violet photoemission spectroscopy, and photon stimulated desorption techniques using Synchrotron radiation. For a saturation dose at 100 K, the SO2 is molecularly adsorbed and a chemisorbed interface is formed by SO42− and SO32− species on the surface. Annealing of the adsorbed layer to room temperature leads to the formation of sulfur derived species.

A study of the MgO(100)–D2O system at 300 K by electron stimulated desorption (ESD) over the energy range up to 600 eV is presented. Auger electron spectroscopy is used as a complementary technique. ESD of the nearly perfect clean surface shows O+ desorbed ions as the main desorbed species with small amounts of H+ and F+ contaminants. The adsorption of D2O produces a dramatic decrease of the O+ intensity in the ESD spectrum and new signals corresponding to D+ and OD+ ions are observed. There is a first energy threshold at about 30 eV for D+ and H+ desorbed ions and a second one at 55 eV for O+ desorbed ions. The desorption of these ions corresponds to a primary excitation of the O 2s (24 eV) and Mg 2p (55 eV) core levels, respectively. The ion kinetic energy distribution of the desorbed O+ ion from the clean surface has two peaks at energies of 6 and 9 eV. The ion kinetic energy distribution of the D+ desorbed ions also shows a bimodal structure with most probable kinetic energies of 3 and 6.5 eV at 150 e...

The adsorption of acetic acid on the TiO 2 (110) surface has been studied with PES, using synchrotron radiation ∼47 eV, both at the stoichiometric (1 × 1) surface and the (1 × 2)-reconstructed surface. The results indicate a similar bonding configuration for each surface, and that the saturation acetate coverage at room temperature on the (1 × 2)-reconstructed surface is approximately half that of the (1 × 1) surface. The results are interpreted in favour of the added Ti 2 O 3 -row model of the (1 × 2) reconstruction at the clean surface.

A review of the Electron Stimulated Desorption, ESD, processes as responsible for producing modification of the gas composition or erroneous readings in those measuring devices using electron beams is presented. After reviewing the basic ESD mechanisms of Menzel-Gomer and Redhead, Feibelman-Knotek and the Auger electron stimulated desorption, some examples of these effects on readings of hot cathode ionization gauges and mass spectrometers are presented. Then, the ESD of H 2 W , H 2 O Nb(110) systems and the ion desorption from a typical transition metal oxide such us the TiO2 (110) are discussed.

Mechanical elements may produce significant contamination of ultrahigh vacuum due to emission of gases from materials under stress and rubbing. Composition of emitted gases and behavior of gas emission was studied for various materials and surface coatings of interest for vacuum engineering. It is suggested that gases dissolved and occluded in the material bulk (H2 and Ar) and tribochemical reactions (CxHy) are the main sources of gas emission. Frictional heating was discarded as the driving force for gas emission. Mathematical apparatus of specific parameters for characterization of gas emission is proposed., This work was carried out with financial support of the Ministry of Science and Innovation of Spain under projects “Ramón y Cajal”RYC-2009-0412 and BIA2011-25653.

CO adsorption on a defective TiO2(110) surface at 150 K incorporating about 1.7 × 1014cm−2 vacancies produced by Ar+ sputtering has been studied by electron stimulated desorption, ESD, and with Auger electron spectroscopy, AES, as a complementary technique. When the surface was exposed to CO up to 5 × 105L the AES spectra revealed a small C signal. From the O(KLL)Ti(LMM) ratio increase a CO coverage of 0.06 ± 0.01 ML was determined. In spite of this small amount of CO the ESD technique showed dramatic changes in ion yield and energy. The characteristic dominant peak at 4.0 eV and the small structure at about 7.0 eV of the ion kinetic energy distribution curve of the clean defective surface changed to a triple peak structure with maxima at 3.4, 4.3 and 7.4 eV. The first is identified with the most probable kinetic energy of O+ ions ejected from non-dissociated CO molecules. The 4.3 and 7.4 eV maxima correspond to the most probable kinetic energy of O+ ions desorbed from O in-plane and from the bridging O-ligand of the TiO2(110) surface, respectively. The growth of the 7.4 eV peak upon adsorption is a consequence of the filling of the bridging O-ligand initial vacancies by dissociated O from the CO molecule. The ion yield curves show, in addition to the onset at 35 eV electron energy of the clean surface, a threshold at about 290 eV electron energy corresponding to excitation of the C 1s core level. The total ion yield also shows a decrease upon CO adsorption. The O+ ion yield curves are found to be related to the secondary electron yield. The chemisorption of CO is discussed in terms of a model where the CO is molecularly adsorbed on the Ti five-fold coordination sites with a part being dissociated and leading to O adsorbed on bridging O-ligand vacancies.

The chemical state and tribological properties of tempered and annealed steels (95MnCrW5 and 30CrMoV12) implanted with C+Ti has been studied by using the Auger sputtering depth profile and the ball on disk method to determine the wear parameters. The sample hardness was measured by the Vickers method. Friction coefficients are reduced by a factor of 0.8 for samples of steel 95MnCrW5 and by a factor of 0.4 for samples of 30CrMoV12 steel. The implanted 95MnCrW5 samples show a phase of mixed amorphous carbon and carbides. The amorphous carbon forms a layer on the surface, while a mixture of TiC and amorphous carbon is really implanted beneath the surface. Molecules of the residual gas containing C are the origin of either the amorphous carbon layer or the contamination of the implanted layer.

We present an investigation of the thermal stability of ESD of O+ ions from the TiO2(110) surface and using AES as a complementary technique. Ion kinetic energy distributions of the ejected species with maxima at 4 and 7.5 eV—previously identified with ions ejected from the O in-plane and the bridging O ligand, respectively—are very sensitive to the thermal treatment of the surface. The intensity of both surface ions depends on the incident electron energy. In general, the ion yield tends to present two maxima at 400 and 700 K, the second one is also shown by the Ti(LMO VB ) Ti(LMV) ratio as a function of temperature. These facts reveal significant changes of the surface structure characterised by modifications of the population of the O in-plane and bridging O ligand. Annealing the surface at temperatures higher than 700 K decreases the intensity of both ion species up to 900 K. AES experiment indicates that above 900 K the inter- to intra-atomic ratio tends to increase.

CO reactivity with a defective (O vacancies, Ar+-sputtered) TiO2(110) surface evaporated with Ta has been studied by electron stimulated desorption, ESD, and using Auger electron spectroscopy, AES, as a complementary technique. The clean surface shows thresholds of the O+-desorbed ions at incident electron energies that can be assigned to ionisation of the Ti 3p, Ta 4f, and 4p core levels. After CO exposure of the surface to saturation with 6 × 104 L, the ion yield shows a significant increase and a new threshold at 290 eV identified with the C 1s excitation is observed. The CO coverage was 0.09 ML, the number of O vacancies before the CO adsorption was 7% of the total number of O atoms of the nearly perfect surface (1.56 × 1015 atoms/cm2) and the AES Ta(NVV)Ti(LMM) ratio was 7%. The O+ ion yield follows quite well the secondary electron yield. Ion energy distribution curves of the O+-desorbed ions show structures that are identified with O+-desorbed ions from O species bonded to Ti and Ta atoms as well as from the CO. About 76% of the adsorbed CO is dissociated.

In this paper we describe an investigation of the ion kinetic energy distribution (IED) with electron stimulated desorption of O+ from SO2 adsorbed on TiO2(110) at 153 K. The IED at the clean surface shows a bimodal structure with two well differentiated peaks, at most probable kinetic energies of 4 and 7.2 eV. The SO2 adsorption produces a dramatic change in the IED. There is a new peak at 2 eV kinetic energy, and the peaks at 4 and 7.2 eV vary in intensity according to the electron incident energy. The O+ ion yield curve shows, in addition to the onset at the Ti 3p core level at 35 eV electron energy, a second threshold at 160 eV corresponding to S 2p core level excitation. Changes in the IED curves following annealing of the SO2 layer at room temperature and 400 K as well as an adsorption model are also presented.

The energy and angular distribution of the electron-stimulated O+ ion yield have been measured from clean and SO2-dosed rutile TiO2(110). ESD spectra from the clean surface indicate ion emission at three energies: 2.5, 4.0 and 6.5 eV. By comparison with previous calculations, the 4.0 and 6.5 eV features can be assigned to emission of in-plane and bridging O atoms, respectively. The elongation of the ESDIAD image in the [110] azimuth is consistent with that predicted for the in-plane O atoms. While the O+ energy distribution changes significantly following SO2 adsorption at 130 K and again following sequential annealing, there is little change to the ESDIAD pattern. The latter result is consistent with emission from surface sulphate species, although it could also be due to a residual substrate effect.

In this paper the composition of the interface of TiN and TiCN hard coatings deposited onto high speed steel substrates obtained by the arc discharge technique is studied using Auger electron spectroscopy at two different substrate temperatures, 520 K and 720 K. The low temperature (520 K) TiN coating developed an oxygen phase at the interface, producing a weak adherence of 40 N, while the high temperature coatings (720 K) has a less intense oxygen phase, giving a greater adherence to the substrate of 60 N. The TiCN coatings at 520 K are characterized by a low oxygen intensity at the interface. However, their adherence of 50 N is lower than the value of 60 N for the high temperature TiN coatings and is independent of the substrate temeperature.

The results of the pioneer research of the phenomenon of a mechanically stimulated solution of gases (hydrogen and deuterium) in a bulk of balls made of carbon chromium steel (15% Cr, 1% C) are presented. The experiments have been performed in a vacuum chamber filled with deuterium at a pressure of 5 ×10 -1 Pa. The ball-bearing was loaded by an axial force of 34.3 N per ball and rotation was performed at a speed of 195 rpm. The phenomenon has been studied for both long (N 1 = 24 x 10 3 revolutions) and short (N 2 = 2 x 10 3 revolutions) rotation periods. An unloaded sample of the same steel was kept stationary in the chamber during the experiment as a reference. The measurements of the distribution of hydrogen and deuterium atoms in the depth of the ball, as well as in the bulk of the reference sample, were performed using SIMS.

The reaction of oxygen on the Nb (110) surface at 240 K after exposure to H2O and O2 under e-bombardment has been investigated by using AES and EELS techniques- The uptake of oxygen atoms is much more efficient when the surface is exposed to H2O than to O2. The chemistry of the oxygen adatoms is analysed on the basis of the AES Nb(M45N23V) and EELS structures. At the highest H2O exposure the oxygen atoms are in the form of Nb2O5 oxide, while for O2 the final state is an oxide of less valence. Initial sticking coefficients of ~ 1 and 0.41 for oxygen and water respectively, at 240 K adsorption temperature, have been determined. A model based on dissociative adsorption and electron stimulated desorption processes is presented to explain the differences between both molecules.

Measurements have been initiated of H+ ion energy distributions from a water dosed Si(100) substrate at room temperature and with multilayer formation at ~ 100 K. The apparently wide energy distributions usually observed with electron stimulated desorption are attributed to desorption along multiple pathways. Increasing the beam energy from 170 to 200 eV causes a shift in the peak position from around 8.5 to 5.7 eV, and is assigned to the role of secondary electrons which increasingly dominate as the energy is increased (seemingly associated with the ionisation of the silicon 2p (L2,3) level). A further peak in the ion energy distribution is emphasised towards low electron energy (< 50 eV) with peak energy at around 3.6 eV. Overall the production of H+ is enhanced with multilayer growth, but similar features of the ion energy distribution are present also at room temperature.

Electron stimulated desorption from the MgO(100) surface has been studied over the energy range up to 500 eV. The observed threshold of the ESD O + desorbed ion from the MgO(100) clean surface at 55eV incident electron energy agrees well with the excitation energy of the Mg 2p core level. The kinetic energy distribution of the O + desorbed ions presents a bi-modal structure with most probable kinetic energies of 6 and 9 eV. The result is possibly influenced by the presence of defects at the (100) surface. These results indicate that the desorption of the O + ions follows the Feibelman-Knotek model for full valence metal oxides. Charging effects at the surface have been taken into account to determine absolute values of ion energy, particularly toward the higher energy range of incident electron energy.

In this work we study the chemisorption of CO on Nb(110) surface under electron bombardment at 240 K using Auger electron spectroscopy, AES, and electron energy loss spectroscopy, EELS, techniques. Electron bombardment proves to be very effective in growing a carbon layer due to the high yield of depopulated O atoms by electron-stimulated desorption. The energy of primary electrons has a significant influence on the rate of carbon accumulation. Low energy electrons, about 250 eV, reveal EELS spectra quite different from those produced by 2000 eV electrons in both structure and intensity.

In the present work, the YBa 2 Cu 3 O 7−x surface and its reactivity with the residual vacuum at room temperature has been characterized using electron-stimulated desorption, ESD, and Auger electron spectroscopy, AES. The samples were prepared by sintering component oxides under pressure. The AES spectra revealed C and Cl as the most usual contaminants. ESD experiments show, in addition to the expected O + surface ions, H + , F + , and Cl + . H + surface ions are more intense than the expected O + surface ions. Thermal cleaning of the sample is rather difficult due to the high porosity of the samples yielding extremely high gas loads. The intensity of the hydrogen species yielding H + are in equilibrium with the H 2 pressure in the system up to a pressure of 10 −9 mbar, beyond which the uptake remains constant.

In this paper the influence of the temperature of the high speed steel (HSS) substrate during the TiN x (0 x =>0.7, as well as surfaces which do not oxidate easily when exposed to atmospheric pressure. The presence of oxygen at the interface produces weak adhesion of the coating, 40N, as compared with the 60 N for the coating without oxygen. The typical thickness of the coatings was about 500 nm and with a hardness of about 2000 kg-f mm −2 .

The energy electron loss spectra (EELS) and the Auger electron spectra (AES) of the clean and C, O, H2O and CH3OH contaminated surfaces of Nb(110) have been studied. The clean surface presents a loss structure at 8.3 eV which changes to 6.8–7.21 eV due to an excitation implying the O(2p) orbital. With the C contaminant the loss occurs at 5.8 eV. The surface and volume plasmons of the clean surface at 17.6 eV energy shifts to 19.5 eV for all the contaminants, due to the disappearance of the surface plasmon. All contaminants reduce the density of the Nb 4d electrons as revealed by the intensity of the M23N45N45 Auger transition at 25 eV energy. The most drastic changes are produced by water adsorption under electron bombardment. The M23N45N45 transition disappears, and instead of it, a new structure at 19 eV energy increases in intensity. This structure is explained as an Auger transition implying electrons of the O(BV). C and C + O contaminants also suppress the 25 eV transition. It is also shown that e− bombardment induces a strong oxidized state. The C + O AES spectrum presents a transition in the region of 19–22 eV energy. The low energy side is related to the O adsorption and the high energy region to the C adsorption. Methanol and water are dissociated as methoxy and hydroxyl radicals respectively.

The adsorption of methanol on the Nb(110) surface has been studied by the electron stimulated desorption (ESD) and thermal desorption spectrometry (TDS) techniques, electron energy loss spectroscopy (EELS) and Auger electron spectroscopy (AES). The main ESD product is H * irrespective of the surface temperature and coverage of the surface. The thermally desorbed gases from a layer adsorbed at a temperature of 240 K are CH 4 , H 2 and CO. The ion energy distribution (IED) reveals a most probable kinetic energy of 8 eV that shifts to 5.6 eV at higher exposures. The initial layer is mainly formed by methoxy species, that are dissociated into an intermediate with an energy of 71 kJ mol −1 .

Ultraviolet photoelectron spectroscopy (UPS) and probe-hole thermal desorption spectrometry have been used to study the adsorption of water on two TiO2(001) surfaces: (i) Nearly perfect surface, 6% of Ti+3 point defects, and (ii) defective surface, 24% of Ti+3 point defects. As revealed by the intensities of the 3σ and 1π orbitals, water is dissociated into OH radicals. The coverage of 0.4 ML is the same in both surfaces. The adsorption-desorption reaction path is: Download : Download full-size image where OL is oxygen bridging ligand of the surface. The maximum desorption rate of H2O, the only desorbed species, occurs at 600 K.

Adsorption of SO2 on stoichiometric TiO2(110) at 153K has been studied by electron stimulated desorption (ESD). At this temperature the coverage of SO2 estimated from complementary Auger studies is about 0.27 ML Following SO2 dosing, the ESD O+ ion yield is enhanced for electron energies above 155 eV and 225 eV, and is identified with excitation of the S 2p and 2s core levels. The clean surface has a O+ threshold at 35 eV corresponding to excitation of the Ti 3p level. Changes in ion yield with substrate temperature up to 450 K are described within a model consistent with a recent NEXAFS study which revealed the surface reaction sequence: SO2→SO2− 3 →SO2− 4.

The purpose of the present work is to study the composition of the emitted ions and to characterize the surface composition of MCP as function of temperature using ESD, AES and SEM techniques. It is found, that sodium and potassium have significant contribution to the desorbed ions. Intensity of these elements increased with increasing surface temperature. The presence of water and hydroxyl ions was negligible. Heating of the surface simultaneously with electron bombardment resulted in changes of the chemistry of the surface, which consisted mainly in a decrease of C and in an increase of Na and K on the surface.

A new method to determine gas content in solid materials based on the phenomenon of gas desorption induced by mechanical action, i.e. friction, indentation, etc., has been developed. Absorbed gases including hydrogen and helium can be analyzed using this method in both bulk or thin film materials. The sensitivity of the method for most gases is below 10 ppm of atomic concentration, while depth resolution is below 1 micrometer. The study of the effect of adsorption and readsorption of the desorbed molecules on the accuracy, sensitivity and the dynamic range of measurements is discussed. Experimental validation of the method has been done using normal and deuterated stainless steel samples.

Preliminary results on the electron damage of a CH3OH (methanol) layer adsorbed on Nb(110) studied by ESD, ELS and AES are presented. After methanol dosing and before the e− bombardment the ESD spectrum reveals H+ surface ions. Under e− bombardment the H+ surface ion current decreases exponentially with time to a constant value while the e− beam induced ESD O+ surface ion current increases linearly with time. Total ESD cross section determined from the H+ decay is 5.5×l0−19 cm2. The ion energy distribution experiments reveal two kinds of ions with most probable kinetic energy of 8 eV and 5 eV. The high energy peak shifts to the lower one as a function of e− dosing. The initial layer, mainly formed by methoxy species, is completely dissociated as O, H and C as a consequence of the electron bombardment.