A study of titanium nitride diffusion barriers between aluminum and silicon by X-ray absorption spectroscopy: the Si, Ti and N results.

We report a multi-elment, multi-edge and multi-detection mode X-ray photoabsorption study of a series of Al/TiN(x)/Si(100) thin films as a function of the TiN(x) film thickness (100A-500A) and of the annealing temperature (400 degrees C-600 degrees C). The Si K- and L-edge results show that Si does not diffuse to the surface for all the films. The high resolution Ti L-edge and N K-edge spectra show that the TiN(x) layer undergoes a dramatic chemical reaction with the gradual increase in the annealing temperature. This chemical reaction stabilizes at 560 degrees C at which the TiN(x) film is known to fail to act as an effective diffusion barrier between Al and Si.

First results from the Canadian SGM beamline at SRC.

The first experimental results obtained from the Canadian SGM beamline at SRC (Synchrotron Radiation Centre, University of Wisconsin-Madison, USA) are reported. The beamline is based on the Dragon-type design, with a constant deviation angle, using photons from a second-generation bending-magnet light source. The medium-energy grating on this beamline covers a photon energy range from 240 to 700 eV, with a ruling density of 600 lines mm(-1). A maximum resolving power of approximately 10000 is achieved at a photon energy of approximately 400 eV. Gas-phase absorption spectra collected at the N, O and C K-edges are presented to demonstrate the excellent performance of this beamline. High-resolution absorption spectra of some C- and Ti-containing solid-state samples are also reported.

Variable-energy photoelectron spectroscopy of substituted rhenium and manganese pentacarbonyls: molecular orbital assignments and the interatomic resonant effect.

High-resolution variable-energy photoelectron spectra of M(CO)5X [M = Re, X = Re(CO)5, Cl, Br, and I; and M = Mn, X = Mn(CO)5 and Br] are reported. Tunable synchrotron radiation is used to distinguish the Re 5d and Br 4p orbital based peaks for the controversial Re(CO)5Br. Our results provide firm molecular orbital assignments for all of these molecules. The valence orbital in the ordering of ionization energies for M(CO)5Cl (M = Mn and Re) and Mn(CO)5Br is a 1(M-X) > e(X) > b2(M) > e(M); but for M(CO)5I (M = Mn and Re) and Re(CO)5Br the ordering is a1(M-X) > e(M) > b2(M) > e(X). The crossover of the HOMO in the Re molecules due to the change in the halogen electronegativities occurs at Re(CO)5Br. The metal np-->nd resonance is observed for all of these molecules. For molecules like M2(CO)10 (M = Re and Mn) and Mn(CO)5Br, the observation of this np-->nd resonance is useful in assigning the metal nd based orbitals in their valence level spectra. However, for molecules like Re(CO)5X (X = Br and Cl), a np-->nd type resonance is observed on bands arising from both Re 5d and halogen mp based orbitals. This new resonant effect on the ligand-based orbitals is shown to be mainly due to the interatomic resonant effect. The core and valence level chemical shifts of these compounds are treated using Jolly's approach to confirm the assignments for the valence level spectra of some of these molecules. The high-resolution inner valence and core level spectra of these compounds are reported. Broadening of Re 4f, Br 3d, and I 4d core level spectra is discussed. The Auger peaks are observed in the high-resolution, high-intensity Br 3d of Re(CO)5Br and I 4d of Re(CO)5I spectra.

Variable-Energy Photoelectron Spectroscopy of (eta(5)-C(5)H(5))NiNO: Molecular Orbital Assignment and Xalpha-SW Calculations.

Variable-energy valence and inner-valence photoelectron spectra have been recorded for the CpNiNO complex (Cp = eta(5)-C(5)H(5)) between 21.2 and 100 eV, using He I radiation and synchrotron radiation. The ground state electronic structure has been calculated by using the Xalpha-SW method. Photoionization cross sections (sigma) have also been calculated for the valence ionizations using the Xalpha-SW method. The theoretical branching ratios (sigma(i)/ summation operatorsigma) have been compared with the observed branching ratios (A(i)()/ summation operatorA) between 21.2 and 100 eV. The assignment of the photoelectron spectrum based on the analysis of intensity variations and width of vibrational peaks is consistent with the ion state orbital ordering 5e(1)(1) < 7a(1)(2) < 3e(2)(3) < 4e(1)(4) (band numbers are in parentheses) and is inconsistent with another recently proposed ordering 5e(1)(1), 5e(1)(2) < 7a(1), 3e(2)(3) < 4e(1)(4), which takes the 5e(1) vibronic effects into consideration. The experimental branching ratio results indicate a Ni 3p resonance effect around 75 eV in the photoionization process. The inner-valence spectrum has also been assigned with the aid of the Xalpha-SW calculations.

Diffraction and mossbauer studies of minerals from lunar soils and rocks.

Constituents of lunar soils and rocks were studied by powder and singlecrystal x-ray diffraction. In addition to identification of minerals, including rare amphibole, mica, and aragonite, a detailed study of the important rock-forming minerals of the plagioclase, pyroxene, and olivine groups has begun. Mössbauer spectra were recorded from lunar soils, ground rock samples, and separates of iron-bearing minerals. The proportions of iron-bearing minerals were estimated from computer-fitted areas for the bulk samples. The Fe(2+) in the lower-density fraction of pyroxene was ordered, whereas that of the higher-density fraction was disordered.