L-EDGE XANES STUDIES OF CHARGE REDISTRIBUTION UPON COMPOUND FORMATION IN GOLD AND NICKEL METALLIC COMPOUNDS

L-edge XANES of a series of gold (AuAl2, AuGa2 and Au2Ag) and nickel (NiSb, Ni0.64 Fe0.36 NiAl, and NiAl ) intermetallic compounds have been measured. It is found that the LIII.II edges of AuAl2 and AuGa2 exhibit very intense whiteline indicating a significant depletion of d character at the Au site of these compounds. This observation is interpreted in terms of a mechanism in which s-d interplay determines the overall charge redistribution. In the case of Ni compounds, the effect of s-d interplay is found to be less dramatic

Si Core Level XANES of Organometallic Compounds Containing Si-Ge Bonds: Experimental and Theoretical Observations

Si K- and L2,3-edge XANES for Si(GeMe3)4 and Ge(SiMe3)4 are studied with the aid of MS-Xα calculation. Good agreement is found between the experiment and the theory. The lowest energy features are assigned to the transitions to mostly unoccupied orbitals with significant Si-Ge contribution

OXYGEN K-EDGE ABSORPTION SPECTRA OF SMALL MOLECULES IN THE GAS PHASE

The absorption spectra of O2, CO, CO2 and OCS have been recorded in a transmission mode in the energy region from 500 to 950 eV. Recent observation of EXAFS in these molecules is confirmed in this study

X-RAY ABSORPTION MEASUREMENTS OF ORGANIC SOLUTIONS OF ORGANOMETALLICS WITH SCINTILLATION COUNTING METHODS

We report a new technique with which X-ray absorption measurements of solutions can be made by counting the X-ray induced luminescence from the sample. This technique (scintillation yield) involves the addition of a small amount of scintillator to the sample solution. Simultaneous measurements of X-ray absorption spectra of (CH3)4 Sn in organic scintillator solutions using photoconductivity and scintillation yield are reported to illustrate the feasibility of this technique

High Resolution Cu L3,2-Edge XANES Studies of Cu-Au Alloys

High resolution Cn L3,2-edge XANES have been obtained for Ca metal and a series of Cu-Au alloys (Cu3-Au, CuAu and. CuAu3). It was found that the Cu L3-edge XAMES for all the samples under investigation exhibit the characteristic three-peak resonances predicted by theory. The Cu L3-edge XANES shows some interesting systematics which can be correlated to charge redistribution in Ca-Au alloys

M3,2-Edge X-Ray Absorption Near Edge Structure of 5d Metals

We report M3,2 edge XANES measurements for a series of 5d metals, Hf, Ta, W, Re, Ir, Pt and Au using a total electron yield technique. It was found that the M3,2 XANES for most 5d metals exhibit intense resonances at the threshold (whitelines). The area under the whitetine correlates with the unoccupied densities of d states of the metal. The M3,2 XANES features and their systematic are comparable to their L3,2 counterparts. These results clearly suggest that M3,2 edge XANES can be ased as an alternative probe to the conventional L3,2 -edge XANES for the unoccupied densities of d states of the 5d metals and their compounds

High Resolution Ag L3-XANES Studies of AuAg Alloys Using the Electron Yield of a Narrow Auger Channel

The Ag L3-XANES for Ag metal and a series of Au-Ag alloys, AuAg3, AuAg and Au3Ag have been obtained by monitoring the intensity of the Ag L3—M4,5M4,5 Auger electrons with high energy resolution. The selected 1G4 final state has a much longer lifetime than the L3 core hole which results in a reduced lifetime broadening of the partial yield spectra. Subtle features which are predicted by theory and barely visible in total yield spectra are clearly resolved here. The experiment confirms the earlier conventional XANES observation that Ag gains d charge upon alloying with Au. Full-scale multiple scattering calculations have been carried out for the Ag L3-XANES of Ag and AuAg. The results are discussed in the context of electron charge redistribution and unoccupied densities of states

Resonant L3-M4,5N4,5 Auger electron spectroscopy as a probe for the local electronic structure in PdxAg1-x Alloys, Chiba, Japan 1997

The Pd L3-M4,5N4,5 Auger spectra from the pure metal and severalPdxAg1−x alloys were studied for sub-threshold excitation energies utilising the resonant line narrowing. Upon alloying, a characteristic line broadening with decreasing palladium concentration is observed. The measured energy shifts in the Auger parameter are in agreement with an increase in the locald-charge density at the palladium sites in thePdxAg1−x alloys

M3,2 and L3,2 XAFS of Au and Pt Nanoparticles on Porous Silicon

XAFS measurements at both the M3,2 and L3,2 edges of Pt and Au as well as scanning electron microscopy studies have been carried out for a series of porous silicon specimens onto which fine particles of Au and Pt with nanometre and tens of nanometre dimensions have been dispersed. A wet chemistry technique developed in our laboratory was used for the deposition. The Au XAFS clearly show that the Au deposits are essentially Au metal while the Pt deposits exhibit features that are noticeably different from that of metallic Pt. The M3,2 and L3,2 the XANES and their implications are discussed