Ar ion sputtering

The SIMS system is mounted on a UHV spectrometer which also has XPS, UPS, LEED and thermal desorption capabilities ( ). Heating is achieved by electron bombardment from a filament mounted on the manipulator behind the sample. Cooling is achieved by circulating liquid N2 or He. Temperatures of 25K can be reached. The samples used, Ni(lOO), Cu(17%) Ni(83%) (100) and (111) and Ag(lll) were oriented within 1 and cleaned in situ by standard heating and Ar ion sputtering procedures. 

The catalytic preformance of Co crystals with two surface conditions were compared annealed crystals with large atomically flat terraces and Ar+ ion sputtered surfaces which produced a high population of surface defects. A sequence of PM-RAIRS spectra are shown in Figure 3.2 during exposure of a sputtered Co (0001) surface to mixtures of H2 and CO, with the temperature and pressure for each spectrum indicated in the figure. 

Fig. 3 Ar+ ion sputtering of a surface, which removes contaminant or oxide layers, exposing a clean surface for analysis... 

A decrease in the O content, measured by XPS, on Ar ion sputtering together with a Cd S ratio close to unity led Danaher et al. to propose that the O (not quantified) was present as surface sulphate [38]. In this same investigation, SIMS analysis (much more sensitive than XPS, which is limited to ca. 0.1% concentration) found a variety of impurities, including decomposition products of thiourea, CdO, and Cd(OH)2, but these were not seen in XPS, showing that they were present in very low concentration. 

The important role played by defect density in chemical reactivity can be seen in Figure 7.8, which shows Is photoemission spectra of a vacuum-cleaved, clean MgO (100) surface in comparison with (1) the Is spectrum of a vacuum-cleaved MgO (100) surface exposed to 2.3 x 10-8 torr p(H20) for 3 min, (2) the spectrum of an MgO (100) surface purposely cleaved off angle in vacuum then exposed to p(H20) = 3 x 10-8 torr for 3 minutes, and (3) the spectrum of an MgO (100) surface that was Ar+ ion sputtered and then exposed to p(H20) = 2.5 x 10 x torr... 

Figure 12. Tin XPS (3d) Spectra of (a) AuSn particles prepared in acetone (b) after Ar ion sputtering.

The sputtering technique consists in bombarding an Ai target with Ar ions accelerated to 5 KeV. The Ar pressure is in the 10 J mbar range, and the target current measured on the Al foil is kept to W pA. Once the Al foil is cleaned by Ar+ ion sputtering for 30 mn, then the polymer film is positioned in front of the Al foil to intercept the sputtered species. 

Anodic aluminum oxide, 312, 401 Antiferromagnetic-like interactions, 141 Antiferromagnetism, 433 Arc discharge method, 448 Ar ion sputtering, 449 Arrhenius, Carl Axel, 4 Arrhenius-Uke behaviour, 134 Asteriod hypothesis, 46 Atomic force microscope (AFM), 397 Atomistic simulation, 296,297 Au(llO), 137 Au(lll), 135... 

The TiOo thin films were first cleaned in UHV by Ar+ ion sputtering followed by oxygen annealing (1100 K, 10-6 mbar 0 ) to restore surface stoichiometry. A Pt film of approximately ID A (based on the attenuation of the Ti XPS signals) was vapor deposited on this defect free TiO2 surface. The Pt film was then sintered by heating to 875 K (2 hr., 10"6 mbar 0o). The size of the Pt particles formed in this manner are estimated to be 2 to 5 nm in diameter based on comparison with microscopy studies in the literature.(18)... 

A polished TiO2(110) wafer of 6.5 x 1 x 0.25 mm3 (Earth Chemical) was used after deposition of Ni film on the rear side of the sample to resistively heat the sample on a sample holder. The surface was cleaned by cycles of Ar + ion sputtering (3 keV for 3 min) and annealing under UHV at 900 K for 30 s until a clear lxl LEED pattern was obtained. Deuterated formic acid (DCOOD, Wako, 98% purity, most of the contaminant is water) was purified by repeated freeze-pump-thaw cycles and introduced into the chamber by backfilling. The surface temperature of the crystal was monitored by an infrared radiation thermometer. 

A Ni(lll) single crystal, oriented to within 0.2° of the (111) plane, is mounted on a manipulator which rotates it 360° around an axis parallel to its surface and translates it in three mutually perpendicular directions while maintaining the ultrahigh vacuum conditions in the main chamber. The crystal can be cooled to 8 K by contact with a liquid He reservoir and can be heated to 1400 K. A chromel-constantan thermocouple is spot-welded to the crystal for temperature measurements. The procedure for cleaning the crystal by Ar ion sputtering, oxidation and reduction has been discussed previously (ref. 5). 

Figure 10. Effect of Ar-ion sputtering on Sn, C and 0 signals in ESCA. (Reproduced with permission from Ref. 20. Copyright 1981, Elsevier Sequoia. )...

Samples Pdl.6 and Pd3.3 have been examined by XPS combined with Ar ion sputtering. Fig. 3 shows binding energies spectra of the Pd3.3 catalyst in the region corresponding to the Pd3d photoelectron doublet (3d3/2,s/2) acquired before (curve (a)) and after (curve (b)) Ar sputtering. The spectrum of a palladium foil is also presented (curve (c)). 

The chemical state analysis was carried out by means of AES (PHI-660) combined with Ar ions sputtering at an energy of 3 keV. 

Electrochemical deposition of Pt ion on Rli(lOO) and Rli ion on Pt(llO) was perfonned in a small volume cubic cell branched out the UHV chamber. Rh(lOO) and Pt(lOO) surfaces were subjected to a cleaning procedme consisting of Ar ion sputtering, O2 treatment (5x10-8 Torr ) at 800 - 1000 K for 10 min, and annealing at 1000 - 1200 K for 20 min. After the cleaning, the crystal was transfered into a cubic cell for electrochemical deposition. The cell was filled... 

S=0)—), but the phenyl ring appears to be unaffected. The core of the PPS polymer particles also remains unchanged under the oxidizing conditions studied, since depth profiling by Ar" " ion sputtering exhibited an increase in the sulphide concentration and a decrease in the sulphone concentration. 

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