نتایج جستجو برای: ionization effect

تعداد نتایج: 1675564  

Journal: :journal of the iranian chemical research 0
ewa daniela raczyńska department of chemistry, warsaw university of life sciences, 02-776 warszawa, poland malgorzta hallmann department of chemistry, warsaw university of life sciences, 02-776 warszawa, poland kinga duczmal department of chemistry, warsaw university of life sciences, 02-776 warszawa, poland

keto-enol tautomerism was investigated for ionized pyruvic acid using the dft(b3lyp) method and the larger basis sets [6-31++g(d,p), 6-311++g(3df, 3pd) and aug-cc-pvdz]. change of the tautomeric preference was observed when going from the neutral to ionized tautomeric mixture. ionization favors the enolization process (ketoenol) of pyruvic acid, whereas the ketonization (ketoenol) is preferred ...

Journal: :iranian journal of science and technology (sciences) 2009
h. sabzyan

time-dependent schrödinger equation for a 1-d model of hydrogen molecular ion h2+ in intenselaser field linearly polarized along the molecular axis is solved. ionization rates are calculated for differentinitial states. the evolution of electronic wavefunction at fixed inter-nuclear separations are simulated andanalyzed. the results obtained for the ground state of this 1-d model of h2+ show ap...

Journal: :iranian journal of science and technology (sciences) 2005
m. h. mahdieh

a three-step selective photo-ionization for gd155 and gd157 isotopes by pulsed laser wasevaluated numerically. due to large thermal neutron absorption cross sections, these two isotopes innatural gadolinium are good candidates as burnable poison to control reactivity early in the fuel cycleand allow extended fuel burn up. rate equations have been used to calculate the dynamics of the isotopepop...

Journal: :iranian journal of science and technology (sciences) 2008
m. r eskandari

the ionization effects of charged particles produced in neutron interactions for boron neutroncapture therapy are considered here using srim monte carlo code. the estimated values of these effects ina plexiglas acrylic phantom are shown to agree well with the available experimental values in high boronconcentration areas. as expected, the ionization effects from lithium and alpha particles are ...

ژورنال: سنجش و ایمنی پرتو 2013

The development of a graphite ionization chamber in Iran is reported for first time, using graphite coatings collecting electrodes and guard rings. Its sensitive volume is about 200cm³, with a shape of a ring which is different from its older equivalents and a 7cm central hole that allows the passage of the direct radiation beam without attenuation. This kind of ionization chamber has alre...

2001
G. G. Paulus F. Grasbon H. Walther W. Becker

Multiphoton resonances with ponderomotively upshifted Rydberg states are believed to have dramatic effects on the plateau of high-order above-threshold ionization. For short pulses and intense laser fields, individual Rydberg states lose their physical significance. Under these conditions, on the basis of experimental and theoretical investigation of the dependence of the photoelectron spectra ...

ژورنال: سنجش و ایمنی پرتو 2014

The use of gaseous ionization to calculate the absorbed dose of radiation beams is attractive because of its relative ease, suitable response, high accuracy and also cost-effectiveness. This work introduces the design and fabrication of a new parallel plate ionization chamber with two sensitive volumes. A series of standard tests was performed with x-rays, gamma radiation units, and beta source...

Journal: :Physical review. A, General physics 1987
Mehler Müller Greiner Soff

We present calculations for the impact-parameter dependence of K-shell ionization rates in p-Cu and in p-Ag collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the antibinding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization ...

2011
Junliang Xu Yaqiu Liang Zhangjin Chen C. D. Lin

We study elastic scattering and impact ionization by returning electrons induced in a strong laser field based on the recently developed quantitative rescattering theory. The high-energy angle-resolved photoelectron spectra of molecules in strong fields are attributed to elastic scattering of the returning electrons with the parent ion. We demonstrate that the high-energy photoelectron spectra ...

ژورنال: سنجش و ایمنی پرتو 2020

According to International Atomic Energy Agency (IAEA) recommendations, the calibration of ionization chambers used for radiotherapy dosimetry follows the substitution method which demands the use of a reference ionization chamber. This work introduces the Design and fabrication of cylindrical ionization chamber for dosimetry to be used by standard dosimetry laboratories. The result of the qual...

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