X-ray fluorescence measurements of x-ray absorption near edge structure at the Si, P, and S L edges

Abstract

High-resolution (≤0.2 eV) x-ray absorption near edge structure (XANES) spectra have been recorded at the Si, P, and S 2p edges of several compounds using microchannel plates to detect the ultrasoft x-ray fluorescence after 2p excitation or ionization. The fluorescence yield (FY) XANES of SiO2, Si, InP, FeS2, and Na2S2O3 are of at least as good quality as the XANES recorded using total electron yield (TEY), despite the extremely small fluorescence yield. The FY spectra obtained show two significant advantages over the TEY spectra. First, the FY XANES is much more bulk sensitive; and second the resolution of the FY spectra is usually considerably better.

Optical Properties of Nanostructured Silicon

“…Figure 18 shows the PEY obtained from bulk Si (spectrum (a)) and passivated Si NCs (spectrum (b)) at the Si L 2,3 edge. Data for bulk silicon are in agreement with previous work [80,81]. However, the absorption spectrum from the NCs is remarkably different from both the bulk and what would be expected from a consideration of the theoretically determined unoccupied density of states (DOS) in silicon clusters containing a few tens of atoms [82,83].…”

“…This behavior is in contrast to the blue shift that has been previously reported for porous Si [81,95], SiO 2 /Si superlattices [96], and for Si nanoclusters [28] and attributed to quantum confinement. A red shift has, however, been reported for 2 and 3 nm diameter silicon clusters formed upon annealing SiO 2 superlattices by Zimina et al [97], although changes in the absorption spectrum were much less pronounced than those reported here.…”

“…However, the absorption spectrum from the NCs is remarkably different from both the bulk and what would be expected from a consideration of the theoretically determined unoccupied density of states (DOS) in silicon clusters containing a few tens of atoms [82,83]. The NC XAS consists of a single, relatively sharp, spin-orbit split peak superimposed upon a smooth background intensity between threshold and the onset of oxide-related absorption (bands at 106, 108 eV and a weak band at 115 eV which are commonly attributed to inner well resonances of Si oxide [81,[84][85][86]). The relatively high strength of the oxide features in the XAS spectra of the Si NCs despite the bulk-sensitive PPY detection can be attributed to the structure of the NC film: passivation of the Si NC Figure 17 Si L 2,3 region total photon yield near-edge X-ray absorption fine structure (NEXAFS) spectrum, two edges at 100 and 104 eV, corresponding to Si and SiO 2 , respectively, which implies that Si-Si and Si-O bonds are present in the sample.…”

Studies on ZDDP Thermal Film Formation by XANES Spectroscopy, Atomic Force Microscopy, FIB/SEM and 31P NMR

“…TEY spectra is more surface sensitive compared to FY spectra [38]. The sampling depths of TEY and FY at the P K-edge are 5 nm and *50 nm respectively [40,41]. A strong single intense peak is characteristic of the phosphorus Kedge, and is attributed to the transition of a phosphorus 1s electron to an empty p-like antibonding state.…”

The Effect of Steel Hardness on the Performance of ZDDP Antiwear Films: A Multi-Technique Approach

“…Phosphorus K-edge spectra were obtained at the DCM beam line, which covers an energy range of 1,500-4,000 eV, with a resolution of 0.8 eV. The phosphorus K-edge spectra were both recorded in the total electron yield (TEY) and fluorescence yield (FY) modes for surface and bulk sensitivity [42], respectively. Phosphorus L-edge spectra were collected at the Grasshopper beam line, which covers an energy range of 70-900 eV, with a resolution of 0.2 eV.…”