Stability and chemical composition of thermally grown iridium-oxide thin filmsThe effect of thermal growth conditions on the morphology and surface work function of iridium oxide thin films grown by annealing Ir thin films in an O 2 ambient is presented. The samples were analyzed using x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, and photoelectric work function measurements. It is found that, with increasing temperature, IrO 2 changes from ͑110͒ oriented to a mixture of ͑110͒ and ͑200͒ during the oxide growth. This is manifested as a sharpening of the photoelectric energy distributions at 800°C. The surface work function was determined to be 4.23 eV using ultraviolet photoelectron spectroscopy. X-ray photoelectron spectroscopy analysis shows that IrO 2 starts to form at 600°C accompanied by surface roughening. Annealing the Ir film at 900°C in O 2 ambient leads to almost complete desorption of the film.

Relative measurements of e -Ar angular distributions in the energy range 3 -20 eV have been placed on an absolute scale by both a phase-shift analysis and relative Aow normalization. The two sets of absolute differential cross sections are in excellent agreement with each other over the entire energy range. These measurements are also in agreement with previous calculations and measurements in different energy and angular ranges. Total cross sections calculated from the derived phase shifts are in excellent agreement with recent direct experimental determinations.

The deposition of metal nanoparticles (such as Ag, Cu, Au, Pd, and Pt) on boron-doped, polycrystalline diamond thin films grown on silicon substrates was investigated using Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Nanometer-size metal particles with preferred crystalline textures can be spontaneously deposited on the diamond thin film after a simple immersion in an acidic solution containing metal ions or metal complex ions. The size and distribution of metal deposits can be controlled by adjusting the metal ions concentration, the solution acidity, and the deposition time. The diamond/silicon interfacial ohmic contact was found to be the critical factor for achieving the observed spontaneous metal deposition on the diamond surface. Significant enhancement of hydrogen evolution activity was observed on a diamond electrode modified by 9% coverage of Pd nanoparticles. The results demonstrate a novel route for depositing nanometer-size metal catalysts on a highly corrosion resistant and dimensionally stable polycrystalline diamond support.

to be 26% of the total yield at 1 MeV for a 2-mm-thick silicon crystal. The yields due to Coulomb scattering were determined by integrating the Gaussian peak and correcting for the yield in the low-energy tail.The experimental cross sections da/d2 were reduced from the measured yields by use of the following relation:dar/d£l=N/AQqt.The quantity N is the yield of electrons measured in a known solid angle Aft at a given scattering angle. The quantity t is the number of target atoms per cm 2 normal to the beam direction and is determined from the target thickness. The quantity q is the number of electrons incident on the target. The measured cross sections were compared to the Mott cross sections which were calculated by Doggett and Spencer. 2 These comparisons are shown in Fig. 4 where the differential cross section da/dti for Coulomb scattering without atomic excitation, normalized to the PHYSICAL REVIEW The Ramsauer technique has been used to measure the absolute total electron-helium-atom scattering cross section as a function of electron energy from 0.30 to 28 eV with an estimated probable error of ±3%. No "fine structure" has been observed at the lower electron energies studied. The variation of the cross section with energy for energies less than 3 eV is in reasonable agreement with the modified effective-range formula given by O'Malley, using a scattering length of 1.15a 0 . The cross section first increases with decreasing electron energy from 2.2 A 2 at 28.0 eV to a maximum of 5.6 A 2 at about 1.2 eV and then decreases to 5.4 A 2 at 0.300 eV. The cross section has been found to decrease sharply with increasing energy at about 0.5 eV below the first excitation energy. This resonance, predicted by Baranger and Gerjuoy and originally observed by Schulz, first decreases with increasing energy to a minimum of about 10% below the background at 19.285=1=0.025 eV and then increases to a gentle maximum of about 3% above the background at 19.65i0.05 eV. The resolution of this resonance as well as the 10% decrease in the cross section at the minimum is determined by the half-width of the electron beam at this energy which is about 0.1 eV. e-He SCATTERINGCROSS SECTIONS

fulfilled, and we reduced the probabilities by empirical factors gained from measurements of neon. 4 CONCLUSIONSBy measuring relative abundances of multiply charged ions of krypton, produced by x-ray bombardment, we were able to demonstrate the existence of the double Auger process 3d-NNN in which two electrons are ejected. Such a process has previously been observed in neon and argon for transitions to the outermost shells, but in the case of krypton an unusually large intensity of 0.3 relative to the single Auger process was obtained.