scholarly journals Angle-dependent interferences in electron emission accompanying stimulated Compton scattering from molecules

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Arturo Sopena ◽  
Alicia Palacios ◽  
Fabrice Catoire ◽  
Henri Bachau ◽  
Fernando Martín
Keyword(s):  
Compton Scattering ◽  
Cross Sections ◽  
Electron Emission ◽  
Molecular Orientation ◽  
Angular Distributions ◽  
Free Electrons ◽  
Orthogonal Direction ◽  
Linear Processes ◽  
X Ray ◽  
Propagation Axis

AbstractThe high brilliance of ultrashort X-ray pulses recently generated in free electron lasers will soon open the way to the investigation of non-linear processes that still remain inaccessible due to the smallness of the corresponding cross sections. One of them is stimulated Compton scattering from molecules. In this work, we investigate stimulated Compton scattering from fixed-in-space H2 molecules in the few-hundred eV photon energy range, where both dipole and non-dipole transitions are important. We show that the interference between dipole and non-dipole transitions leads to pronounced asymmetries in the electron angular distributions. These asymmetries strongly depend on molecular orientation, to the point that they can lead to electron emission in either the forward or the backward directions with respect to the propagation axis, or in both directions, or even in the orthogonal direction. This is in contrast with Compton scattering from free electrons or atomic targets.

OBSERVATION OF INTERFERENCE BETWEEN ATOMIC BREMSSTRAHLUNG AND NUCLEAR BREMSSTRAHLUNG

1999 ◽  
Vol 09 (01n02) ◽  
pp. 1-10 ◽  
Author(s):  
K. ISHII ◽  
T. SATOH ◽  
S. MATSUYAMA ◽  
H. YAMAZAKI ◽  
Y. TOKAI ◽  
...  
Keyword(s):  
Cross Sections ◽  
Energy Region ◽  
Production Cross ◽  
Angular Distributions ◽  
X Rays ◽  
Beam Direction ◽  
Aluminum Target ◽  
X Ray ◽  
Wide Range ◽  
Mev Protons

An aluminum target was bombarded with 1.5 MeV protons and continuous x-rays were measured at the angles of 45°, 90° and 135° with respect to the beam direction. By investigating the shape of the x-ray energy spectrum, it was recognized that, the continuous x-rays below 12 keV are atomic bremsstrahlung (AB) and those of above 12 keV are nuclear bremsstrahlung (NB), and AB and NB are mingled in the energy region of around 12 keV The x-ray energy dependence of angular distributions presented well a change from the process of AB to that of NB in the continuous x-ray spectrum. Interference between AB and NB were discussed on the basis of PWBA theory. Continuous x-ray production cross sections were calculated on the basis of PWBA BEA and a semi-classical theory and compared with the experimental results. The theoretical prediction reproduced well the experimental cross sections over the wide range of 6 orders in magnitude and of 2 keV – 35 keV in the energy except for the energy region mingled with AB and NB. The ratio of the theoretical cross sections to the experimental ones showed an interference effect between AB and NB in their mingled region.

scholarly journals Transverse Momentum Transfer Distributions Following Single Ionization in 3.6 MeV/amu Au53+ + He Collisions: A 4-Body Classical Treatment

Atoms ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 68 ◽  
Author(s):  
François Frémont
Keyword(s):  
Transverse Momentum ◽  
Momentum Transfer ◽  
Cross Sections ◽  
Electron Emission ◽  
Differential Cross ◽  
Classical Model ◽  
Equations Of Motion ◽  
Free Electrons ◽  
Hamilton Equations ◽  
Momentum Distributions

A four-body classical model based on the resolution of Hamilton equations of motion was used here to determine and analyze ionization doubly-differential cross sections following 3.6 MeV/amu Au53+ + He collisions. Our calculation was not able to reproduce the binary peaks experimentally observed in the transverse momentum distributions for electron emission energies larger than 10 eV. Surprisingly, by introducing a large number of free or quasi-free electrons that followed the projectile at the same velocity, the agreement between the experiment and our calculation was improved, since our model reproduced, at least qualitatively, the experimental binary peaks. The origin of the presence of such electrons is discussed.

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

L X-RAY FLUORESCENCE CROSS-SECTIONS MEASUREMENTS FOR ELEMENTS 56≤Z≤66 IN THE ENERGY RANGE 11-41 keV

1987 ◽  
Vol 48 (C9) ◽  
pp. C8-669-C8-672 ◽  
Author(s):  
S. SINGH ◽  
S. KUMAR ◽  
D. MEHTA ◽  
M. L. GARG ◽  
N. SINGH ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
X Ray

Morphology and Affinities of Ampelocissites Seeds (Vitaceae: Ampelopsis clade) from the Paleogene of Texas, USA

2020 ◽  
Vol 45 (3) ◽  
pp. 478-482
Author(s):  
Steven R. Manchester
Keyword(s):  
Computed Tomography ◽  
Cross Sections ◽  
Seed Coat ◽  
Ct Scanning ◽  
Seed Morphology ◽  
Early Eocene ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Fossil Seeds ◽  
Fossil Genus

Abstract—The type material on which the fossil genus name Ampelocissites was established in 1929 has been reexamined with the aid of X-ray micro-computed tomography (μ-CT) scanning and compared with seeds of extant taxa to assess the relationships of these fossils within the grape family, Vitaceae. The specimens were collected from a sandstone of late Paleocene or early Eocene age. Although originally inferred by Berry to be intermediate in morphology between Ampelocissus and Vitis, the newly revealed details of seed morphology indicate that these seeds represent instead the Ampelopsis clade. Digital cross sections show that the seed coat maintains its thickness over the external surfaces, but diminishes quickly in the ventral infolds. This feature, along with the elliptical chalaza and lack of an apical groove, indicate that Ampelocissites lytlensis Berry probably represents Ampelopsis or Nekemias (rather than Ampelocissus or Vitis) and that the generic name Ampelocissites may be useful for fossil seeds with morphology consistent with the Ampelopsis clade that lack sufficient characters to specify placement within one of these extant genera.

scholarly journals Effect on Compton Scattering Spectra by Hermite–Gaussian Light

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 650
Author(s):  
Akane Agui ◽  
Hiroshi Sakurai ◽  
Naruki Tsuji ◽  
Haruka Ito ◽  
Kiyofumi Nitta
Keyword(s):  
Compton Scattering ◽  
X Rays ◽  
Harmonic Order ◽  
X Ray ◽  
Scattering Spectra

In this study, we measured the Compton scattering spectra of Al, Ag and Au metals changing the harmonic order of X-rays from an undulator. The width of the Compton scattered X-ray spectrum changed depending on the harmonic order of X-rays. This indicates that Compton scattering spectra shape reflects a momentum perpendicular to the traveling direction in Hermite–Gaussian (HG) light.

Doubly differential electron emission cross sections for He0 (0.5 MeV/amu) ? He collisions

1991 ◽  
Vol 21 (S1) ◽  
pp. S333-S335
Author(s):  
O. Heil ◽  
R. Maier ◽  
R. D. DuBois ◽  
M. Kuzel ◽  
K. O. Groeneveld
Keyword(s):  
Cross Sections ◽  
Electron Emission
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