scholarly journals Enhanced fluorescence from x-ray line coincidence pumping of K-pumped Cl and Mg-pumped Ge plasmas

2019 ◽  
Author(s):  
Joseph Nilsen ◽  
D. Burridge ◽  
L.M. R. Hobbs ◽  
D. Hoarty ◽  
P. Beiersdorfer ◽  
...  
Keyword(s):  
Enhanced Fluorescence ◽  
X Ray

scholarly journals Enhanced fluorescence of selected cationic dyes adsorbed on reduced-charge montmorillonite

Clay Minerals ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 93-103 ◽  
Author(s):  
P. Pustková ◽  
Z. Klika ◽  
J. Preclíková ◽  
T. M. Grygar
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Nile Blue ◽  
Cationic Dyes ◽  
X Ray Diffraction ◽  
Enhanced Fluorescence ◽  
Visible Absorption ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe aggregation of three cationic dyes (CD), crystal violet (CV), Nile blue (NB) and rhodamine B (RB) in aqueous solution was studied by visible absorption spectrophotometry and compared with methylene blue (MB). The distribution of the dye species (monomers, dimers, trimers, and tetramers) in aqueous solutions with different concentrations of dye was calculated using equilibrium stepwise aggregation constants Kn. These cationic dyes were intercalated into montmorillonite (SAz-1) and its reduced charge form (RC-SAz(210)) prepared by heating lithium montmorillonite (Li/SAz-1) at 210ºC. The fluorescence of fully saturated CD/SAz and low-CD loaded CD/RC-SAz(210) complexes was studied. Visible absorption spectra of CD aqueous solutions and visible absorption spectra and X-ray diffraction patterns (d001) of the CD/SAz and CD/RC-SAz( 210) solid complexes were obtained and evaluated. Large fluorescence intensities were found for CV/RC-SAz(210) and NB/RC-SAz(210) complexes in the same way as for the complex of methylene blue with reduced-charge montmorillonite MB/RCM(210) described previously.

Ar K X-ray production in slow, highly charged Ar q+(q = 8–18) + Ar collisions

2002 ◽  
Vol 80 (12) ◽  
pp. 1579-1589 ◽  
Author(s):  
H Tawara ◽  
P Richard
Keyword(s):  
Cross Sections ◽  
X Rays ◽  
Enhanced Fluorescence ◽  
Energy Correlation ◽  
X Ray ◽  
Ion Collisions ◽  
Wide Range ◽  
First Time ◽  
Rotational Coupling ◽  
Shell Vacancy

In the present work, mechanisms of Ar K X-ray production have been investigated under low-energy Arq+ + Ar collisions in a wide range of the ion-charge states. Ar K X-rays have been observed as a function of the collision energy over (0.75–3.75)q keV/u and of the charge state over q = 8–16 of projectile Arq+ ions. If the L-shell vacancies become available (q = 9), Ar K X-ray yields are found to be enhanced roughly three orders of magnitude, compared with Ar8+ ions with no L-shell vacancy; to show some threshold; and to tend to quickly saturate at higher collision energies. The present analysis, based on the energy correlation diagrams of the quasi-molecules, suggests that Ar K X-rays originate entirely from target Ar atoms through promotion via the rotational coupling between 2pσ –2pπ molecular orbitals. Furthermore, the observed cross sections are found to increase nonlinearly with the projectile Arq+ ion charge q (q = 9). This can be understood because of the combined effects of two contributions: (i) the increased number of the L-shell vacancies of projectile Arq+ ions and (ii) the enhanced fluorescence yields of target Ar atom. In addition, Ar K X-rays have been observed under 2.5q keV/u Ar17+ and Ar18+ + Ar collisions and found to originate from the decay of K-shell vacancies initially present in the projectile Ar ions through electron capture into their highly excited states, followed by cascade down to the ground states. For the first time, though very weak, the X-rays due to the two-electron–one-photon transition, namely, K αα lines, have also been observed in bare Ar18+ ion collisions. PACS Nos.: 34.70+e, 32.80Rm

scholarly journals Enhanced Fluorescence from X-Ray Line Coincidence Pumping

2020 ◽  
pp. 29-35
Author(s):  
J. Nilsen ◽  
D. Burridge ◽  
L. M. R. Hobbs ◽  
D. Hoarty ◽  
P. Beiersdorfer ◽  
...  
Keyword(s):  
Enhanced Fluorescence ◽  
X Ray

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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