The characterisation of non-evaporable getters by Auger electron spectroscopy: analytical potential and artefacts

Abstract

The surfaces of getter materials are particularly difficult to analyse because of their high chemical reactivity. The results obtained can be strongly influenced by the experimental setup and procedures. In this paper the experimental influence on the Auger electron spectroscopy results is discussed, based on the measurements of more than 100 different non-evaporable getter (NEG) materials. There are four typical changes in the Auger electron spectra when a NEG becomes activated. The oxygen peak intensity decreases, the shape of the metal peaks changes, the carbon peak shape changes shape and intensity and a chlorine peak occurs. All these changes are affected by instrumental artefacts. The Zr-MNV peak shape changes occurring during the reduction of ZrO 2 are well suited to determine the onset of NEG activation, while the slope with which the O-KLL peak intensity decreases in a certain temperature range is a better criterion for the determination of the temperature at which activation is complete. The O-KLL intensity and the Zr-MNV peak shape are influenced by the adsorption of residual gas, in particular of H 2 O, and by electron stimulated desorption of oxygen. The C-KLL peak shape changes from "graphitic" to "carbidic" when the NEG becomes activated. The changes of the C-KLL intensity observed in the present study are mainly caused by the transfer of carbon contamination from the sample holder onto the sample during NEG heating. The presence of chlorine at submonolayer coverage is easily detected by AES but not by XPS. The temperature at which a Cl-LMM peak appears in the NEG Auger electron spectra is correlated with the onset of NEG activation. The Cl-LMM intensity is strongly reduced by electron irradiation, in particular when AES measurements are carried out on hot samples.

Protecting Carbon Nanotubes from Oxidation for Selective Carbon Impurity Elimination

“…also Supporting Information, Figure S3). This hypothesis is also supported by the AES of this CNT sample for which chlorine could be well detected 69 [Figure 6a and Fourier transform infrared (FTIR) results, Supporting Information, Figure S4]. XPS analysis also revealed the presence of chlorine species at the surface of mD (Figure 6b).…”

Some Key Issues of Vacuum System Design in Accelerators and Colliders

“…The research results showed that the concentrations of Ti and Zr were enriched on the surface of activated Ti-Zr-V NEG films [108,109]. The oxygen detected on the activated surface was mainly in the form of Zirconium suboxides and titanium suboxides.…”

The interaction of Zr2Fe surface with O2 and H2O at the temperature range 300–770K

“…NEG materials have long been used in the industry for a variety of applications, which need maintaining of ultra-high-vacuum (UHV) such as high energy particle accelerators [1][2][3]. The most common NEG materials are metals, such as Zr, Ti, Nb, Ta, V that have a wide solubility range towards oxygen or hydrogen and alloys based on those metals.…”

“…The NEG are usually easy to apply and manufacture as powder, pellets, thin layers, etc. [1][2][3]. Zr 2 Fe was found to be effective in scavenging hydrogen down to very low concentrations and can be used, for example, to prevent the release of tritiated heavy water [4] or for fuel purification in a fusion fuel cycle [5].…”