Results 1 - 10 of 8495
Results 1 - 10 of 8495. Search took: 0.034 seconds
|Sort by: date | relevance|
[en] This paper presents Auger electron spectroscopy with a retarding field analyser designed for an advanced physics experiment carried out in 'Physics Laboratory II' at the Institute of Experimental Physics, University of Wroclaw, Poland. The authors discuss the process of setting up the experiment and the results of the measurement of Auger spectra. The advantages and disadvantages of the apparatus are discussed along with its implementation in the teaching process
[en] Calibration is required to obtain analyte concentrations in atomic spectrometry. To take full benefit of it, the adequacy of the coefficient of determination r2 is discussed, and its use is compared with the uncertainty due to the prediction bands of the regression. Also discussed from a tutorial point of view are the influence of the weighting procedure and of different weighting factors, and the comparison between linear and quadratic regression to cope with curvatures. They are illustrated with examples based on the use of ICP-AES with nebulization and laser ablation, and of LIBS. Use of a calibration graph over several orders of magnitude may be problematic as well as the use of a quadratic regression to cope with possible curvatures. Instrument softwares that allow reprocessing of the calibration by selecting standards around the expected analyte concentration are convenient for optimizing the calibration procedure.
[en] Analytical expressions and numerical results describing ionization of atoms by intense linearly polarized ultrashort laser pulses are obtained in the frame of the Keldysh approach. Photoelectron spectra and total ionization probabilities are presented for several analytical models of a single-cycle laser pulse. In particular, strong left-right asymmetry of the spectra is shown for the case of odd pulses.
[en] The distribution of core level binding energies in disordered metallic alloys is reviewed. Results of ab initio calculations and experimental electron spectroscopy are reviewed and interpreted using intuitive charge models that emphasize the underlying physics. The opportunity for exploiting the core disorder broadening phenomenon for environment-resolved spectroscopy is discussed.
[en] The 'disorder broadening' of core level binding energies in disordered metallic alloys is considered. The origin and magnitude of the effect in bulk alloys is discussed, with particular reference to an intuitive charge model that emphasizes the underlying physics. The model is also used to simulate the core level photoelectron spectra derived from the surface region of various disordered systems.
[en] The photoelectron (PE) spectra of some 3-monosubstituted 2-methylpropenes H2C=C(CH3)CH2X [X = Cl, Br, I, OH, OMe, OEt, SH, SMe, SEt, N(Me)2 and N(Et)2] have been recorded. A preliminary analysis is presented indicating some trends in the ionization potentials associated with application of OVGF method and NBO analysis from MP2/6-31G(d,p) and cc-pVDZ level of theory indicating that the more effective hyperconjugation effect leads to the most stable conformers. The sensitivity of the outermost ionization energies of selected molecules with respect to the level of theory was analyzed. Application of the CASPT2 method with ANO basis set and geometries from MP2 calculations provided results in excellent agreement with the experimental data
[en] A discrete two-hole one-particle (2hlp) shakeup/down state can decay either by spectator Auger transitions or by participant Auger transitions. The 2hlp state created by the participant Auger transition of the 2hlp shakeup/down state can be the same as the one created by the Auger transition of the 1h state. The participant Auger transition by which the electron excited by the shakeup/down fills the core hole, can be dominant. If this is so, when the two discrete core-hole states couple to the same continuum and their separation energy is smaller than or comparable to the core-hole lifetime width, there is a possibility of an interference between the Auger transition of the 1h state and the participant Auger transition of the 2hlp state. The screening of the Auger electron emission of the 1h state via the participant Auger transition of the 2hlp state leads to a pronounced interference in the Auger-electron spectroscopy (AES) spectrum. Because the screening function behaves like a Fano resonance. As the function is critically energy dependent, the photoelectron spectroscopy (PES) line peaks do not coincide with the AES ones, when the latter ones are shifted by the 2h final-state energy. In such a case, the PES line peak measured in coincidence with the AES one is shifted from the noncoincidence PES one. When the photoelectron is collected in coincidence with the Auger electron (or X-ray fluorescence) for a selected decay channel, i.e., when the doubly differential photoionization cross section of the photoelectron and the Auger electron (or X-ray fluorescence) being emitted and collected in coincidence is integrated over the Auger-electron kinetic energies (or X-ray fluorescence energies) of the selected decay channel and summed for the final states of the selected decay channel, the photoelectron spectrum is the noncoincidence (singles) photoelectron spectrum weighted by the branching ratio of the partial decay rate of the selected decay channel so that we can extract the screening function by comparing the coincidence photoelectron spectrum with the singles (noncoincidence) photoelectron one
[en] Since their theoretical prediction a decade ago, interatomic (intermolecular) Coulombic decay (ICD) and related processes have been in the focus of intensive theoretical and experimental research. The spectacular progress in this direction has been stimulated both by the fundamental importance of the new electronic decay phenomena and by the exciting possibility of their practical application, for example in spectroscopy. We review the current status of the research of interatomic (intermolecular) decay phenomena in clusters and discuss some perspectives of this new field
[en] X-ray photoelectron spectroscopy (XPS), also called electron spectroscopy for chemical analysis (ESCA), is widely used both in basic research and in analysis of materials, particularly in surface analysis. Using XPS we can obtain information on the elemental surface composition (except for H and He), and the electronic structure of the materials involved. This paper will briefly review the principle of XPS, basic qualitative and quantitative data analysis methods, and some application examples. (authors)
[en] Plasmons in metallic nanomaterials exhibit very strong size and shape effects, and thus have recently gained considerable attention in nanotechnology, information technology, and life science. In this review, we overview the fundamental properties of plasmons in materials with various dimensionalities and discuss the optical functional properties of localized plasmon polaritons in nanometer-scale to atomic-scale objects. First, the pioneering works on plasmons by electron energy loss spectroscopy are briefly surveyed. Then, we discuss the effects of atomistic charge dynamics on the dispersion relation of propagating plasmon modes, such as those for planar crystal surface, atomic sheets and straight atomic wires. Finally, standing-wave plasmons, or antenna resonances of plasmon polariton, of some widely used nanometer-scale structures and atomic-scale wires (the smallest possible plasmonic building blocks) are exemplified along with their applications. (topical review)