Photoelectron spectroscopy in materials science and physical chemistry (original) (raw)

X-ray photoelectron spectroscopy of gaseous atoms and molecules

1980

A versatile gas phase x-ray photoelectron spectrometer employing a PDP 8/e minicomputer to control the spectrometer functions and data accumulation is described. Facilities for heating materials inside the spectrometer to ^10 00°C are currently available, and the advantages of such are suitably demonstrated. Core level x-ray photoelectron spectra of the Group IA metal atoms, sodium, potassium, rubidium, cesium and the Group IIA metal atoms, magnesium, calcium, strontium, and barium have been obtained. These provide the first accurate measurements of the core binding energies for several of these elements. Experimental and theoretical values from the literature are compared with the present results. The free atom binding energies are found to be greater than the comparative solid state binding energies. The experimental "phase transition shifts" are compared with various theoretical estimates. Multielectron excitation satel-v-TABLE OF CONTENTS Page CHAPTER ONE: INTRODUCTION 1 References 11 CHAPTER TWO: BASIC CONCEPTS OF X-RAY PHOTOELECTRON SPECTROSCOPY 14 2.1 Introduction 14 2.2 N-Electron Wave Functions 15 2.3 Molecular Orbital Calculations For XPS Studies 21 2.4 Koopmans 1 Theorem and Binding Energies 25 2.5 Further Binding Energy Calculations.. 2 7 2.6 Configuration Interaction Method .... 29 2.7 Transition Probabilities and Photoelectron Cross-Sections 31 2.8 Sudden Approximation 35 2.9 Sum Rules on Energy and Intensity 40 2.10 Core Binding Energy Shifts 4 3 2.11 Relaxation Effects on Binding Energy 4 7 2.11.1 Atoms 4 8 2.11.2 Molecules 51 2.11.3 Solids 52 2.11.4 Core Level Binding Energy Shifts in Metals 54 2.12 Multicomponent Structure in XPS 60 2.12.1 Spin-Orbit Splitting 60 2.12.2 Multiplet Splitting 62 2.12.3 Multielectron Excitations ..

A Chemical View on X‐ray Photoelectron Spectroscopy: the ESCA Molecule and Surface‐to‐Bulk XPS Shifts

ChemPhysChem, 2017

In this paper we remind the reader of a simple, intuitive picture of chemical shifts in X‐ray photoelectron spectroscopy (XPS) as the difference in chemical bonding between the probed atom and its neighbor to the right in the periodic table, the so called Z+1 approximation. We use the classical ESCA molecule, ethyl trifluoroacetate, and 4d‐transition metals to explicitly demonstrate agreement between core‐level shifts computed as differences between final core‐hole states and the approach where each core‐ionized atom is replaced by a Z+1 atom. In this final state, or total energy picture, the XPS shift arises due to the more or less unfavorable chemical bonding of the effective nitrogen in the carbon geometry for the ESCA molecule. Surface core level shifts in metals are determined by whether the Z+1 atom as an alloy segregates to the surface or is more soluble in the bulk. As further illustration of this more chemical picture, we compare the geometry of C 1s and O 1s core‐ionized C...

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

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.

Photoelectron spectroscopy—An overview

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2005

We give an overview about the development of photoelectron spectroscopy (PES) from first historic observations of the photoelectric effect to state-of-the-art experiments. We present selected examples for the application of PES for chemical analysis of solids (ESCA), the determination of the valence band structure by angle resolved photoelectron spectroscopy (ARUPS), and the investigation of many-body effects by high-resolution PES. Furthermore, we give a brief introduction to the possibilities of spacially resolved PES and PES with high photon energies.

XPS for chemical- and charge-sensitive analyses

Thin Solid Films, 2013

By recording X-ray photoelectron spectroscopic binding energy shifts, while subjecting samples to a variety of optical and electrical stimuli, information about charge accumulation on materials or surface structures can be obtained. These stimuli included d.c. as well as a.c. electrical and/or optical pulses covering a wide frequency range (10 −3 to 10 6 Hz) for probing charging and/or photovoltage shifts, stemming from impurities, dopants, defects, etc., whether created intentionally or not. The methodology is simple to implement and provides several new dimensions for thin films and materials analyses.

XPS Binding Energies of Deep Core Levels and the Auger Parameter - An Application to Solid Sulfur Compounds

Acta Physica Polonica A, 1993

X-ray photoelectron spectroscopy/X-ray excited Auger electron spectroscopy investigations of solid sulfur compounds are reported. Deep S s core level binding energies were measured in addition to the common S 2p level and the KLL Auger spectra to derive the Auger parameters. Local and solid state effects on the binding energies were identified using both core levels within an initial state-final state framework. The results are discussed in comparison to recent data on phosphorus compounds. The information from the deep core level is emphasized.