Total reflection X-ray photoelectron spectroscopy: A review (original) (raw)
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Recent developments in instrumentation for x-ray photoelectron spectroscopy
Analytical Chemistry, 1989
X-ray photoelectron spectroscopy (XPS or ESCA) is one of the many electron spectroscopies particularly useful for the chemical analysis of surfaces. The technique, based on the photoemission of electrons induced by soft X-rays, is widely used for detailed surface analytical problem solving hecause it allows multiple-element detection, provides chemical bonding and state information from chemical shifts, and provides quantitative information.
X-ray Photoelectron Spectroscopy
Journal of the Japan Society of Colour Material, 1991
X-ray photoelectron spectroscopy (XPS) is a non-destructive technique used to analyze the elemental compositions, chemical and electronic states of materials. XPS has a depth of analysis from 1 to 10nm. Chemical studies can be performed with more depth if surfaces are removed or etched. Samples need to be cleaned and free of surface
Journal of Physics D, 2021
Near total reflection regime has been widely used in X-ray science, specifically in grazing incidence small angle X-ray scattering and in hard X-ray photoelectron spectroscopy. In this work, we introduce some practical aspects of using near total reflection in ambient pressure X-ray photoelectron spectroscopy and apply this technique to study chemical concentration gradients in a substrate/photoresist system. Experimental data are accompanied by X-ray optical and photoemission simulations to quantitatively probe the photoresist and the interface with the depth accuracy of ~1 nm. Together, our calculations and experiments confirm that near total reflection X-ray photoelectron spectroscopy is a suitable method to extract information from buried interfaces with highest depth-resolution, which can help address open research questions regarding our understanding of concentration profiles, electrical gradients, and charge transfer phenomena at such interfaces. The presented methodology is especially attractive for solid/liquid interface studies, since it provides all the strengths of a Bragg-reflection standing-wave spectroscopy without the need of an artificial multilayer mirror serving as a standing wave generator, thus dramatically simplifying the sample synthesis.
Two-Dimensional X-ray Photoelectron Spectroscopy for Composite Surface Analysis
Analytical Chemistry, 2008
We describe a method for obtaining two-dimensional X-ray photoelectron spectroscopic data derived from the frequency dependence of the XPS peaks recorded under electrical square-wave pulses, which control and affect the binding energy positions via the electrical potentials developed as a result of charging. By using cross-correlations between various peaks, our technique enables us to elucidate electrical characteristics of surface structures of composite samples and bring out various correlations between hidden/overlapping peaks.
Surface and Interface Analysis, 2024
Strategies to deal with sample charging effects on X-ray photoelectron spectroscopy(XPS) spectra are presented. These strategies combine charge compensation (or lackof) via a flow of electrons and an electrical connection (or lack of) of samples to theground. Practical examples involving samples with a range of different electrical prop-erties, sample structure/composition and sensitivity to X-rays, illustrate the correla-tion between sample properties, measurement strategies, and the resulting XPS data.The most appropriate measurement strategy for a particular sample is also recom-mended. We highlight the crucial importance of appropriate XPS data acquisition toobtain a correct data interpretation
On line shape analysis in X-ray photoelectron spectroscopy
Surface Science, 2001
Any solid state X-ray photoelectron spectrum (XPS) contains contributions due to multiple inelastic scattering in the bulk, surface excitations, energy losses originating from the screening of the ®nal state hole (intrinsic losses), and, for non-monochromatized incident radiation, ghost lines originating from the X-ray satellites. In the present paper it is shown how all these contributions can be consecutively removed from an experimental spectrum employing a single general deconvolution procedure. Application of this method is possible whenever the contributions mentioned above are uncorrelated. It is shown that this is usually true in XPS to a good approximation. The method is illustrated on experimental non-monochromatized MgKa spectra of Au acquired at dierent detection angles but for the same angle of incidence of the X-rays. Ó
The alignment of spectrometers and quantitative measurements in X-ray photoelectron spectroscopy
Journal of Electron Spectroscopy and Related Phenomena, 1997
The alignment of the sample in X-ray photoelectron spectrometers is usually made to optimize the spectral intensities. There are two important classes of spectrometer: (i) those in which the analyser acceptance area is independent of the analysed electron kinetic energy; and (ii) those in which this area varies. Model experiments show how an example of a VG ESCALAB II conforms to class (i) whereas an example of an SSI X-probe is of class (ii) and shows an analyser acceptance area which depends approximately inversely on the emitted electron kinetic energy. This latter result means that the SSI X-probe spectrometer must be aligned for the electrons of the highest kinetic energy (smallest analyser acceptance area). A misalignment of 0.1 mm in the sample height can cause a 10% change in the relative intensities between 0 and 1000 eV binding energies. This dependence of the analyser acceptance area with energy is an effect likely to be common in the advanced electron optical systems of modern electron spectrometers and should be understood in order to use such spectrometers effectively. Such dependencies should be determined by analysts for their own instruments in the operating mode that is used for conducting work in which the repeatability of intensity measurements is important.
On the relation between X-ray Photoelectron Spectroscopy and XAFS
Journal of Physics: Conference Series, 2013
XAFS and X-ray Photoelectron Spectroscopy (XPS) are element specific techniques used in a great variety of research fields. The near edge regime of XAFS provides information on the unoccupied electronic states of a system. For the detailed interpretation of the XAFS results, input from XPS is crucial. The combination of the two techniques is also the basis for the so called core-hole clock technique. One of the important aspects of photoelectron spectroscopy is its chemical sensitivity and that one can obtain detailed information about the composition of a sample. We have for a series of carbon based model molecules carefully investigated the relationship between core level photoelectron intensities and stoichiometry. We find strong EXAFS-like modulations of the core ionization cross sections as function of photon energy and that the intensities at high photon energies converge towards values that do not correspond to the stoichiometric ratios. The photoelectron intensities are dependent on the local molecular structure around the ionized atoms. These effects are well described by molecular calculations using multiple scattering theory and by considering the effects due to monopole shake-up and shake-off as well as to intramolecular inelastic scattering processes.