نتایج جستجو برای: ray absorption

تعداد نتایج: 419388  

Journal: :The Journal of chemical physics 2012
K Nilson J Åhlund M-N Shariati J Schiessling P Palmgren B Brena E Göthelid F Hennies Y Huismans F Evangelista P Rudolf M Göthelid N Mårtensson C Puglia

X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In addition, the comparison of valence band photoemission spectra with the density functional theory...

2003
M. Hävecker A. Knop-Gericke R. W. Mayer M. Fait H. Bluhm

We present the V L3 near edge X-ray absorption fine structure (NEXAFS) of a vanadium phosphorus oxide (VPO) catalyst. The spe ctrum is related to the V3d-O2p hybridised unoccupied states. The overall peak position at the V L3-absorption edge is determined by the formal oxidation state of the absorbing vanadium atom. Details of the absorption fine structure are influenced by the geometric struct...

2007
Roberto Maiolino Guido Risaliti

We review some of the main physical and statistical properties of the X-ray absorber in AGNs. In particular, we review the distribution of the absorbing column density inferred from X-ray observations of various AGN samples. We discuss the location of the X-ray absorber and the relation with the dust absorption at optical and infrared wavelengths. Finally, we shortly review the recent findings ...

Journal: :international journal of nano dimension 0
m. r. khanlary physics department of imam khomeini international university, qazvin, iran s. ghammamy chemistry department of imam khomeini international university, qazvin, iran m. ghomi gilvaee physics department of imam khomeini international university, qazvin, iran

in this research calcium fluoride nanoparticles and its different amount of cerium ion dopant (5%and 10%) were prepared. the mentioned nanoparticle were studied by fourier transform infrared spectroscopy (ftir) , x-ray diffraction (xrd), absorption and photoluminescence spectra (pl) and scanning electron microscopy (sem). the xrd patterns indicate a typical cubic fluorite structure and no other...

2014
J. Gaudin C. Fourment B. I. Cho K. Engelhorn E. Galtier M. Harmand P. M. Leguay H. J. Lee B. Nagler M. Nakatsutsumi C. Ozkan M. Störmer S. Toleikis Th Tschentscher P. A. Heimann F. Dorchies

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called "molecular movie" within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses...

1997
K. S. O'Flaherty

Using the known properties and statistics of intervening quasar absorption systems, we calculate the cumulative absorption out to high redshifts at soft X-ray (E < 1 keV) energies. Although photoelectric absorption in quasar absorption systems provides a signiicant source of opacity at the lowest X-ray energies, the imprint of this absorption is not readily observable since it is generally mask...

2001
Bassem M. Sabra Joseph C. Shields

We present Chandra observations of two radio-quiet QSOs, PG 2302+029 and PG 1254+047. PG2302+029 has an ultra high-velocity UV absorption system (∼ −56, 000 km s), while PG 1254+047 is a Broad Absorption Line (BAL) QSO with detached troughs. Both objects are X-ray weak, consistent with the known correlation between αox and the strength of the UV absorption lines. The data suggest that there is ...

Journal: :Microscopy research and technique 2011
Joy C Andrews Florian Meirer Yijin Liu Zoltan Mester Piero Pianetta

Imaging of cellular structure and extended tissue in biological materials requires nanometer resolution and good sample penetration, which can be provided by current full-field transmission X-ray microscopic techniques in the soft and hard X-ray regions. The various capabilities of full-field transmission X-ray microscopy (TXM) include 3D tomography, Zernike phase contrast, quantification of ab...

M. Ghomi Gilvaee M. R. Khanlary, Sh. Ghammamy

Calcium fluoride nanoparticles with special amount of cerium ion (%1) were synthesized by coprecipitation. Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), absorption and photoluminescence (PL) from CaF2Ce nanoparticles has been investigated. FTIR spectra reveal that there are some amounts of OH, NO3 and other organic functional groups on the parti...

2002
W. N. Brandt S. Kaspi

X-ray absorption and emission lines now serve as powerful diagnostics of the outflows from active galaxies. Detailed X-ray line studies of outflows have recently been enabled for a significant number of active galaxies via the grating spectrometers on Chandra and XMM-Newton. We will review some of the recent X-ray findings on active galaxy outflows from an observational perspective. We also des...

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