Comparative study of the around-Fermi electronic structure of 5d metals and metal-oxides by means of high-resolution X-ray emission and absorption spectroscopies

Abstract

The composition of occupied and unoccupied electronic states in the vicinity of Fermi energies is vital for all materials and relates to their physical, chemical and mechanical properties. This work demonstrates how the combination of resonant and non-resonant X-ray emission spectroscopies supplemented with theoretical modelling allows for quantitative analysis of electronic states in 5d transition metal and metal-oxide materials. Application of X-rays provides element selectivity that, in combination with the penetrating properties of hard X-rays, allows determination of the composition of electronic states under working conditions, i.e. non-vacuum environment. Tungsten metal and tungsten oxide are evaluated to show the capability to simultaneously assess composition of around-band-gap electronic states as well as the character and magnitude of the crystal field splitting.

Recent Developments in Effective Antioxidants: The Structure and Antioxidant Properties

“…The work [ 120 ] describes how the combination of resonant and non-resonant X-ray emission spectroscopies completed by model calculations allows for quantitative analysis of electronic states in 5d transition metal and metal-oxide materials. The use of X-rays supplies element selectivity that, in combination with the hard X-rays, enables the determination of the electronic state’s composition.…”

“…The functional properties of transition-metal-based materials are susceptible to the electronic band structure of the central transition metal. The elemental composition and the presence of defects or lattice distortions have a strong impact on these properties [ 120 ].…”

“…The electronic structure of transition metal elements, especially orbital contribution and the relative energy position of the highest occupied and the lowest unoccupied states, is of significant importance for the design of efficient antioxidants. According to [ 120 ], by tuning the incident energy around the absorption edge of the element, the unoccupied states are probed by electron excitation to the intermediate atomic state. At the same time, the information about the occupied electronic levels can be received by the X-ray photons detection released during the breakup of the intermediate state to the final atomic state.…”

“…It is worth emphasizing that the routine-used electron-based methods, such as X-ray photoelectron spectroscopy (XPS), are often unable to specify the metal electronic states because they cannot be conducted under working conditions [ 120 ]. The X-ray emission and absorption spectra show initial and final electronic state distributions that can be modified by the effects of core-hole screening, natural lifetime broadenings of initial and final states, and transition probabilities [ 120 , 123 ]. In opposite to data given by XAS/XES technique, XPS can provide only the knowledge about the occupied electronic final state [ 123 ].…”

Lifetime effects and satellites in the photoelectron spectrum of tungsten metal

“…Tungsten-based alloys and intermetallic compounds find applications as diffusion barriers in metallization schemes for semiconductor devices due to their chemical inertness towards the surrounding materials and high chemical blocking efficiency [12][13][14][15]. The functionality and reliability of these materials is to a large extent governed by the electronic structure of the base metal [16]. Moreover, when characterizing the properties of tungsten-based compounds, studies often necessitate com-* a.regoutz@ucl.ac.uk parison to those of tungsten metal to elucidate differences.…”