42,475 research outputs found
Presentation and development of a Physics experiment devised for didactic learning: The Lambert-Beer-Bouguer law
No full textThe Lambert-Beer-Bouguer law refers to the decay of the intensity of a radiation travelling through a dissipative medium. Due to the simple phenomenology and to the easiness of the realization of an experimental apparatus for its verification and measure, such law represents, from a didactic point of view, a powerful tool to illustrate the basic features of the exponential decay behaviour to undergraduate students. This paper describes how such purpose can be reached by employing simple equipment and very accessible formalism
Design and test of a lens system for a high energy and high resolution electron spectrometer RID G-7348-2011
No full textWe describe the design and the laboratory test of an electrostatic input lens developed for high energy (> 5 keV) and high resolution photoelectron spectrometers. The lens is part of a hemispherical electron energy analyzer and is designed to optimize the overall accepted solid angle, taking into account the constraints due to the acceptance of the hemispherical dispersing element. In particular, the lens can be operated with two different polarization schemes enabling to obtain high and constant linear magnification (M-1 = 12 and M-1 = 20) in a large interval of retarding factor ranging from an acceleration of 5 to a retardation of 600 (dynamical range of 3000) by the same mechanical layout. These features make such an electrostatic input element a considerable improvement in the technical challenge to perform high quality experiments in high energy photoemission. (c) 2005 Elsevier B.V. All rights reserved
A teaser made simple: a didactic measurement of the spectral answer of a human-eye-calibrated lux meter
No full textA simple didactic experiment has been designed and realized, in order to illustrate to undergraduate students in scientific faculties some basic concepts lying behind the fundamentals of geometrical optics. The spectral response of a human-eye-calibrated lux meter was measured using a very trivial experimental arrangement. The white light of a halogen lamp was decomposed into its spectral components through a diffraction grating, so that collecting the radiation at different dispersion angles allowed one to measure the intensity as a function of wavelength. The experiment can be used to effectively illustrate the concepts of spectral distribution, the radiometry versus photometry conversion and photopic response, and the famous historical experience by Herschel on the 'temperature of colours'
M(3)M(45)M(45) Auger lineshape measured from the Cu(111) surface: Multiplet term selectivity in angle-resolved Auger-photoelectron coincidence spectroscopy
No full textThe capability of the recently observed dichroic effect in angle-resolved Auger-photoelectron coincidence spectroscopy (DEAR-APECS) to disentangle individual multiplet terms has been exploited to study the lineshape of the M(3)M(45)M(45) Auger spectrum measured in coincidence with the 3p(3/2) photoelectrons from the Cu(111) surface. The relevant multiplet structure of the two hole final state is determined with an unprecedented sensitivity, including a reliable experimental estimation of the energy of the (1)D multiplet term. Spectroscopic data for the 3p photoemission feature are also given and energy conservation applied to the photoelectron-Auger-electron pair has been successfully used in order to quantitatively explain energy shifts in coincidence spectra. Multiple-scattering calculations prove that the DEAR-APECS effect is not destroyed by diffraction effects and a simple model which combines atomic angular distributions and electron-diffraction modulations is provided in order to obtain a detailed understanding of the multiplet energy and intensity distributions in Auger spectra
Presentation and development of a physics experiment devised for didactic learning: The lambert-beer-bouguer law
No full textThe Lambert-Beer-Bouguer law refers to the decay of the intensity of a radiation travelling through a dissipative medium. Due to the simple phenomenology and to the easiness of the realization of an experimental apparatus for its verification and measure, such law represents, from a didactic point of view, a powerful tool to illustrate the basic features of the exponential decay behaviour to undergraduate students. This paper describes how such purpose can be reached by employing simple equipment and very accessible formalism
A teaser made simple: a didactic measurement of the spectral answer of a human eye calibrated luxmeter
No full textA simple didactic experiment has been designed and realized, in order to
illustrate to undergraduate students in scientific faculties some basic concepts
lying behind the fundamentals of geometrical optics. The spectral response of a
human-eye-calibrated lux meterwas measured using a very trivial experimental
arrangement. The white light of a halogen lamp was decomposed into its
spectral components through a diffraction grating, so that collecting the
radiation at different dispersion angles allowed one to measure the intensity as a
function of wavelength. The experiment can be used to effectively illustrate the
concepts of spectral distribution, the radiometry versus photometry conversion
and photopic response, and the famous historical experience by Herschel on
the ‘temperature of colours’
Insight on Hole-Hole Interaction and Magnetic Order from Dichroic Auger-Photoelectron Coincidence Spectra
No full textThe absence of sharp structures in the core-valence-valence Auger
line shapes of partially filled bands has severely limited
the use of electron spectroscopy in magnetic crystals and other correlated materials.
Here by a
novel interplay of experimental and theoretical techniques we achieve
a combined understanding of the Photoelectron,
Auger %
and Auger-Photoelectron Coincidence
Spectra (APECS) of CoO. This is a prototype antiferromagnetic material in which
the recently discovered Dichroic Effect in Angle Resolved (DEAR) APECS reveals a complex
pattern in the strongly correlated Auger line shape.
A calculation of the \textit{unrelaxed} spectral features explains
the pattern in detail, labeling the final states by the total spin.
The present theoretical analysis shows that the dichroic effect
arises from a spin-dependence of the angular distribution of the photoelectron-Auger electron
pair detected in coincidence, and from the selective power
of the dichroic technique in assigning different weights to the
various spin components. Since the spin-dependence
of the angular distribution exists in the antiferromagnetic state but vanishes at the N\'eel
temperature, the DEAR-APECS technique detects the phase transition from
its local effects, thus providing a unique tool to
observe and understand magnetic correlations in such circumstances, where the usual methods (neutron diffraction, specific heat measurements) are not applicable
Erratum to: Effect of moderate red wine intake on cardiac prognosis after recent acute myocardial infarction of subjects with Type 2 diabetes mellitus (Diabetic Medicine, (2006), 23, 9, (974-981), 10.1111/j.1464-5491.2006.01886.x)
No full textIn an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola.In an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola
Spin selectivity by Auger-photoelectron coincidence spectroscopy
No full textThe M(3)M(4,5)M(4,5) Auger transition from a Cu(111) surface is studied using Angular Resolved Auger-PhotoElectron Coincidence Spectroscopy (AR-APECS). In the experiment two different geometrical configurations of the electron analyzers allow us to sample different emission angles of the ejected electrons leading to different weights of the singlet and triplet contributions in the studied transition. The experimental spectra are modeled within a two-step approach using the Cini theory for the closed band case so as to properly consider the spin-orbit interaction and the hole-hole correlation energy. Ingredients for the theory, like density of states, are obtained fully ab-initio in the framework of density functional theory by performing all-electron calculations. The obtained results confirm the recently discovered selectivity of AR-APECS in the final spin-state. RI Fratesi, Guido/A-4637-2010; Da Pieve, Fabiana /G-2497-201
[Memo from Lieutenant Colonel M. F. Hass, Civil Affairs Division, with amendments to an evacuation proposal]
No full textA memorandum sent form Lieutenant General M. F. Hass, Civil Affairs Division, which has two corrections from a an evacuation proposal originally sent on May 13, 1942. The correction changes the destination to the Merced Assembly Center.The War Relocation Authority (WRA), together with the Wartime Civil Control Administration (WCCA), the Civil Affairs Division (CAD) and the Office of the Commanding General (OFG) of the Western Defense Command (WDC) operated together to segregate and house some 110,000 men women and children from 1942 to 1945. The collection contains documents and photographs relating to the establishment and administrative workings of the (WDC), the (WRA) and the (WCCA) for the year 1942
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