No abstract available

[en] CdS 'Q-state' particles, with average diameters varying from 2 nm to 10 nm, grown in arachidic acid Langmuir-Blodgett (LB) films, deposited onto optically transparent glass electrodes (OTES), were exposed to H₂ Se(g) to form the corresponding Q-state Cd S_x Se_(1-x) particles. Those particles are considered to be made up of a core of CdS and coated with a monolayer of Cd Se. Q-state Cd S-x Se_(1-x) particle formation was verified by X-ray photoelectron spectroscopy (XPS) and by monitoring a red shift in the UV-visible absorbance spectra relative to that of Cds. XPS results on 5 nm diameter CdS particles that had been grown in an LB film and then extensively exposed to H₂ S (g) revealed a stable average composition of Cd S₀.₄ Se₀₆. A study of the photoelectrochemical behaviour of these systems was conducted through current the open-circuit voltage and a marked increase in the short-circuit current was observed when LB films with Q-state CdS particles were exposed to H₂ Se(g). (author)

[en] Routine evaluation in X-ray photoelectron spectrometry comprises the standard evaluation steps 1) energy calibration 2) sample charging 3) spectrum processing 4) binding energy 5) layer thickness determination 6) quantitative analytics. This work shows the foundations and describes the development of computer codes for an on-site evaluation of measurement data with the help of an EPSON HX-20 computer. (Author, translated by G.Q.)

[en] Thanks to funding from FAPESP we will be installing in the beginning of 1997 a work station for electron spectroscopy designed for the study of clean solid surfaces and the modification of these surfaces by deposition in situ of ultra thin metallic films. The main analytical tool will be a high resolution hemispherical analyzer made by VSW-Omicrom (EA 125 HR) which is capable of better than 5 meV resolution and high transmission due to its five channeltron multi detection system. The system will also have a Rear View LEED Optics for single crystal studies. The system will be housed in a 16'' cylindrical chamber with mu metal magnetic shielding having two levels for analysis. The upper level will contain instruments for technique which do not require photons such as LEED and sample cleaning. The lower level will have the electron analyzer, conventional X-ray source (Al/Mg), electron gun for Auger, e-beam evaporators for thin film deposition and ports for the future addition of different detectors. We will have a manipulator with 5 degrees of freedom (thre translation and two rotational) and sample heating and LN cooling. Finally we will have a fast entry/preparation chamber. The pumping system will have a combination of turbomolecular and ion pumps for the main chamber and a turbo for the fast entr/prep chamber. The system will be used initially for the study of surface alloys by XPS and Photoelectron Diffraction but as soon as it is properly characterized it will be open for collaborations with other groups interested in using its capabilities. (author)

[en] Short communication

[en] Short note

No abstract available

[en] Full text: Auger spectroscopy was first observed and explained correctly by Pierre Auger in 1925 in cloud chamber experiments with radio active sources. The origin of the electrons that know bear his name is a multi-electron process in which an inner core electron is removed, one fills this vacancy and a third, the Auger electron is emitted carrying the energy from the difference in binding energy of the other two electrons and a term due to the energy of the ion in its final state. The strength of Auger spectroscopy is that it is relatively easy to produce Auger electrons. Any ionising radiation that can generate such an inner shell vacancy can be used to generate a source of Auger electrons. Hence they are seen in the electron energy distribution curves in XPS. They appear in these spectra as features that are often broader than XPS peaks, and at energies that are independent of the energy of the incident radiation. Similarly, they can be seen in electron energy distribution curves resulting from direct electron bombardment of the surface. In this case the peaks appear on the electron energy loss curve, and often it is convenient differentiate this signal to separate out the Auger peak from the background. The real strength of Auger spectroscopy for surface analysis is then that a highly focussed electron beam can be used to raster the surface and to generate an image of the surface with the electron energy analyser set to pass a particular Auger line. In this way the technique can be used to map surface elemental distributions with high spatial resolution. The complexity of Auger analysis comes from the fact that there are at least three electrons involved in the process, and that there are many possible configurations for the electrons in the final state. The holes that are left in the atom by the process interact, and the strength of this interaction can have a profound effect on the shape of the Auger line. At Murdoch we have been studying the fundamentals of Auger spectroscopy through looking at Auger lines in coincidence with the XPS electrons that initiated the process. In this way we have been able to simplify the spectra, and to gain some insight into some of the less obvious processes that occur. Copyright (1999) Australian X-ray Analytical Association Inc

[en] Ultra violet inverse photoelectron spectroscopy (uv-ipes) is a powerful technique for the investigation of alkali metals on metal surfaces because most of the alkali metal show chemical and physical properties, which are related to their unoccupied states. In this study, it is found that the uv-ipes spectra provides the intensity of the unoccupied states which decreases with increasing na coverage at off-normal incidence of the electron beam. It is also found that the uv-ipes spectra at 17 and 19 ev incident electron energies presents a shift toward fermi level on the peak at ∼7.8 ev with increasing na coverage

[en] With new and advanced analytical imaging methods emerging, the limits of physical analysis capabilities and furthermore of data acquisition quantities are constantly pushed, claiming high demands to the field of scientific data processing and visualisation. Physical analysis methods like Secondary Ion Mass Spectrometry (SIMS) or Auger Electron Spectroscopy (AES) and others are capable of delivering high-resolution multispectral two-dimensional and three-dimensional image data; usually this multispectral data is available in form of n separate image files with each showing one element or other singular aspect of the sample. There is high need for digital image processing methods enabling the analytical scientist, confronted with such amounts of data routinely, to get rapid insight into the composition of the sample examined, to filter the relevant data and to integrate the information of numerous separate multispectral images to get the complete picture. Sophisticated image processing methods like classification and fusion provide possible solution approaches to this challenge. Classification is a treatment by multivariate statistical means in order to extract analytical information. Image fusion on the other hand denotes a process where images obtained from various sensors or at different moments of time are combined together to provide a more complete picture of a scene or object under investigation. Both techniques are important for the task of information extraction and integration and often one technique depends on the other. Therefore overall aim of this thesis is to evaluate the possibilities of both techniques regarding the task of analytical image processing and to find solutions for the integration and condensation of multispectral analytical image data in order to facilitate the interpretation of the enormous amounts of data routinely acquired by modern physical analysis instruments. (author)