共查询到20条相似文献,搜索用时 15 毫秒
1.
Chemical effects on the Kβ/Kα X-ray intensity ratios
for some Mn, Ni, and Cu complexes of a new schiff-base with salen
N2H2 type were investigated. The samples were excited by 59.543
keV γ-rays from a 241Am annular radioactive source. K X-rays
emitted by samples were counted by a Si(Li) detector with resolution 157 eV
at 5.9 keV. We observed the chemical effect on the Kβ/Kα
X-ray intensity ratios for Mn, Ni and Cu complexes. The experimental
results showed that the Kβ/Kα X-ray intensity ratios
for compounds with complexes are generally larger than those with salt form.
The experimental values have been compared with the other experimental and
the theoretically calculated values of pure elements. The results are in
very good agreement with the others. 相似文献
2.
D. Demir Y. Şahin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):211-216
The effect of external magnetic field on the Kα
and Kβ X-ray production cross-sections and K shell fluorescence
yields for ferromagnetic elements Nd, Gd and Dy and paramagnetic elements Eu
and Ho have been measured at the excitation energy of 59.5 keV γ
-rays from 241Am radioactive source of strength 100 mCi in the
external magnetic field of intensities ±0.75 T. Furthermore,
IKβ /IKα intensity ratios for these elements have been
measured in the external magnetic field. The K X-rays from different targets
were detected using a high resolution Si(Li) semiconductor detector. For B = 0, the measured K X-ray production cross-sections,
K shell fluorescence
yields and the IKβ /IKα intensity ratios were compared
with the experimental and theoretical data in literature. The results have
shown that the fluorescence parameters as photoionization cross section,
fluorescence yield, radiation rates and spectral linewidth can change when
the irradiation is conducted in a magnetic field. 相似文献
3.
The Kα to Lα and Kβ to Lβ intensity ratios of seven elements have been measured following photoionization at 59.5 keV by using a Si (Li) detector
(FWHM=155 eV at 5.96 keV). The intensity ratios were determined by measuring K and L x-rays emitted from a standard target of a given element. The theoretical values of the Kα to Lα and Kβ to Lβ intensity ratios were calculated using theoretically tabulated values of shell/subshell photoionization cross sections,
fluorescence yields, Coster-Kronig transition probabilities, and radiative decay rates for ηKLi≠ and ηKLi=0. The measured values are in good agreement with theoretical results.
From Optika i Spektroskopiya, Vol. 97, No. 2, 2004, pp. 186–189.
Original English Text Copyright ? 2004 by A. Kü?ük?nder, S?ğüt, E. Kü?ük?nder, Büyükkasap.
This article was submitted by the authors in English. 相似文献
4.
A. I. Mikhailov A. V. Nefiodov G. Plunien 《Journal of Experimental and Theoretical Physics》2009,109(5):762-769
We evaluate the total cross section for the single K-shell ionization of atoms and ions by the impact of relativistic electrons.
The study is performed to leading orders of the QED perturbation theory with respect to the parameters αZ and 1/Z. The results obtained are in good agreement with experimental data for different atomic targets. In the case of moderate
values of the nuclear charge Z, the total cross section is described by a simple analytic formula. The K-shell ionization by relativistic heavy particles
is also considered. 相似文献
5.
Total cross sections σif for transfer ionization α + He → He+ + α + e are computed at high energies by means of the four-body continuum distorted wave (CDW-4B) approximation. Comparisons
between the present results σif and the available experimental data at E = 30-600 keV/amu yield satisfactory agreement at impact energies E > 80 keV/amu,
in sharp contrast to the previous independent event model.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Experimental ionization cross sections for K‐shell by protons in target atoms from beryllium to uranium available in the literature from 1953 to 1999 (nearly 5400 values) are collected to deduce the semi‐empirical K‐shell ionization cross sections by fitting the experimental data normalized to their corresponding theoretical values based on the ECPSSR model which accounts for Coulomb deflection, Energy loss of the projectile, Perturbed Stationary State and Relativistic effects, as a function of the reduced velocity parameter. Our results are compared with the experimental data and with the ECPSSR values and reference ionization cross sections obtained by Paul and Sacher [H. Paul and J. Sacher, At. Data. Nucl. Data. Tables 1989 , 42, 105]. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
X. M. Chen J. X. Shao Z. H. Yang H. Q. Zhang Y. Cui X. Xu G. Q. Xiao Y. T. Zhao X. A. Zhang Y. P. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):281-286
Al K-shell X-ray yields are measured with highly charged Arq+ ions
(q=12–16) bombarding against aluminium. The energy range of the Ar
ions is from 180 to 380 keV. K-shell ionization cross sections of aluminium are also obtained from the yields data.
The experimental data is explained within the framework of 2pπ
-2pσ rotational coupling. When Ar ions with 2p-shell vacancies are
incident on aluminium, the vacancies begin to reduce. Meanwhile, collisions
against Al atoms lead to the production of new 2p-shell vacancies of Ar
ions. These Ar 2p-shell vacancies will transfer to the 1s orbit of an Al
atom via 2pπ-2pσ rotational coupling leading to the emission of
a K-shell X-ray of aluminiun. A model is constructed based on the base of
the above physical scenario. The calculation results of the model are in
agreement with the experimental results. 相似文献
8.
A. Küçükönder 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):293-296
The Kα and Kβ X-ray fluorescence cross-sections for the bromide and the iodide compounds were measured by a high-resolution Si(Li) X-ray
detector. The vacancies were produced by heavily filtered 241Am gamma rays. We found that Kα and Kβ X-ray fluorescence cross-sections are changed by chemical effect for different Br and I compounds. Experimental results were
compared with the calculated values of Br and I elements.
Received 15 May 2001 and Received in final form 8 July 2001 相似文献
9.
K. K. Abdullah K. Karunakaran Nair N. Ramachandran K. M. Varier B. R. S. Babu Antony Joseph Rajive Thomas P. Magudapathy K. G. M. Nair 《Pramana》2010,75(3):459-469
Mass attenuation coefficients (μ/ρ) for Zr, Nb, Mo and Pd elements around their K-edges are measured at 14 energies in the range 15.744–28.564 keV using secondary excitation from thin Zr, Nb, Mo, Rh, Pd,
Cd and Sn foils. The measurements were carried out at the K
α
and K
β
energy values of the target elements by two techniques: (1) Proton-induced X-ray emission (PIXE) and (2) 241Am (300 mCi) source. In PIXE, 2 MeV proton-excited X-rays were detected by a Si(Li) detector. In the second case, X-rays excited
by 59.54 keV photons from the targets were counted by an HPGe detector under a narrow beam good geometry set-up with sufficient
shielding. The results are consistent with theoretical values derived from the XCOM package and indicate that the PIXE data
have better statistical accuracy. 相似文献
10.
H. Getahun L. F. Errea C. Illescas L. Méndez I. Rabadán 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):45-49
Single electron capture and single ionization total cross sections in collisions of proton with ethylene are calculated for
an
energy range 25 keV ≤
E
≤ 150 keV, using the classical trajectory Monte Carlo method. Multi-center model potentials are employed to represent
the interaction of the active electron on each molecular orbital with the C2H4+_{4}^{+} core. The results are compared with experimental results for single electron capture. 相似文献
11.
G A V Ramanamurthy K Ramachandra Rao Y Rama Krishna P Venkateswarlu K Bhaskara Rao P V Ramana Rao S Venkata Ratnam V Seshagiri Rao G J Nagaraju S Bhuloka Reddy 《Pramana》2001,56(5):697-703
The Measurement of K
β
K
/α
intensity ratios are measured in some 3d shell elements by using a 2 MeV proton beam along with a high resolution Si(Li) detector. The present Measurement of K
β
K
/α
intensity ratios are in good agreement with Scofield modified theoretical values, thus supporting the basic assumptions in
that theory. From the present Measurement of K
β
K
/α
intensity ratios, it is evident that due to chemical effects, the experimental Measurement of K
β
K
/α
intensity ratios will be increased while they will be decreased due to the presence of simultaneous M-shell vacancies which are produced due to proton excitation. 相似文献
12.
Dr. Minakshi L. K. Jha S. N. Chatterjee B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):331-339
H+ and He2+ impact single and double ionization cross
sections of ground state lead atoms have been calculated in the binary
encounter approximation. Calculations of direct double ionization cross
sections have been performed in the modified double binary encounter model.
The accurate expressions of σΔE (cross-section for energy
transfer ΔE) and Hartree-Fock velocity distributions for the target
electrons have been used throughout the calculations. Contributions to
double ionization from Auger effect following ionization of inner shells
have been considered in the present work. Our H+ impact single and
double ionization cross sections are in good agreement with the experimental
observations. In calculations of He2+ impact cross sections, the
present theoretical approach shows limited success in the experimentally
investigated region (50–350 keV amu-1). 相似文献
13.
D. V. Rao R. Cesareo G. E. Gigante 《Applied Physics A: Materials Science & Processing》1996,62(4):381-386
TotalL X-ray fluorescence cross sections have been measured in the atomic region 39 Z 51 excited by 5.47, 6.47, 7.04, 7.57, 8.14, 8.74 and 9.36 keV photons. Experimental cross sections are compared with the theoretical estimates of Chen et al. based on relativistic Dirac-Hartree-Slater theory. Good agreement is observed between experimental results and theoretical estimates in the studied atomic and energy region. Experimental fluorescence yields have been evaluated using the experimental fluorescence cross sections and theoretical subshell photoionization cross sections. Fluorescence yields are fitted by least squares to fifth-order polynomials inZ of the form
n
a
n
z
n
and compared with theoretical and earlier fitted values. The deviation of the average fluorescence yield in the atomic region 46Z 51 with new theoretical estimates of
, calculated using the ECPSSR (Energy loss Coulomb deflection Perturbed Stationary State Relativistic effects) theory of Brandt and Lapicki and the fitted values clearly indicate the weak dependence of the average fluorescence yield on the initial vacancy distribution. 相似文献
14.
Summary Chemical effects on theKβ/Kα X-ray intensity ratios were investigated for different constitutions of Ti, V, Fe, Se, Br, Zr and Ce by a Ge(Li) X-ray detector.
The vacancies were produced by heavily filtered241Am gamma-rays. It is found that theKβ/Kα X-ray intensity ratios measured with compounds deviated up to 12% from the corresponding values of the pure elements (Ti,
V, Fe) are larger than for the others (Se, Br, Zr and Ce). 相似文献
15.
The K-shell X-ray fluorescence cross sections are determined experimentally for 10 elements such as Pb, Hg, Ir, W, Lu, Tm,
Dy, Tb, Gd and Nd at excitation energy of 661.6 keV associated with γ-rays of 137Cs radioisotope. The technique employed involves the measurement of total intensity of fluorescent K X-rays that follow the
photoeffect absorption of a known flux of γ-rays using a well type Nal(Tl) detector. The obtained results are compared with the available theoretical values and other
measured values. 相似文献
16.
We study the double ionization of the atomic K-shell by a single photon in the relativistic energy domain. The differential and total cross sections of the process are
calculated. It is shown that the ratio of the cross sections of double and single ionization increases with the photon energy,
tending to the limit 0.34/Z
2, where Z is the atomic number or the nuclear charge. The formulas are found to be valid for Z≫1 and αZ≪1, where α=1/137 is the fine-structure constant.
Zh. éksp. Teor. Fiz. 114, 1537–1554 (November 1998) 相似文献
17.
《The European Physical Journal C - Particles and Fields》2007,50(2):315-328
The inclusive production cross sections of the strange vector mesons K*0, K̄*0, and φ have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA
storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central
rapidity region and for transverse momenta up to pT = 3.5 GeV/c. The atomic number dependence is parametrised as σpA=σpN*Aα, where σpN is the proton–nucleon cross section. Within the phase space accessible, α(K*0)=0.86±0.03, α(K̄*0)=0.87±0.03, and α(φ)=0.96±0.02. The total proton–nucleon cross sections, determined by extrapolating the differential measurements
to full phase space, are σpN→K*0=(5.06±0.54) mb, σpN→K̄*0=(4.02±0.45) mb, and σpN→φ=(1.17±0.11) mb. For all resonances the Cronin effect is observed; compared to the measurements of Cronin et al. for K± mesons, the measured values of α for φ mesons coincide with those of K+ mesons for all transverse momenta, while the enhancement for K*0/K̄*0 mesons is smaller. 相似文献
18.
V. A. Khryachkov I. P. Bondarenko B. D. Kuzminov N. N. Semenova A. I. Sergachev 《Physics of Atomic Nuclei》2012,75(4):404-410
The cross section for the reaction 20Ne(n, α)17O was measured in the neutron-energy range 4–7 MeV. An ionization chamber equipped with a Frisch grid combined with a pulse-shape
digitizer was used as a detector. Gaseous neon that served as a target on which the reaction being studied proceeded was added
to the gas filling the ionization chamber. The partial cross sections for the α
0, α
1, α
2, and α
3 channels of the reaction 20Ne(n, α)17O were obtained for the first time. 相似文献
19.
S.N. Nakamura K. Nagamine T. Matsuzaki K. Ishida N. Kawamura S. Sakamoto M. Iwasaki M. Tanase M. Kato K. Kurosawa H. Sugai I. Watanabe K. Kudo N. Takeda G.H. Eaton 《Hyperfine Interactions》1999,118(1-4):209-212
At the RIKEN-RAL Muon Facility, μ- to α sticking K
β
X-rays were observed for the first time taking advantage of the pulsed beam structure. The precision of the present measurements
was insufficient to distinguish between theoretical models, however the observed K
β
/K
α
X-ray intensity ratio tends to be smaller than most of these theoretical predictions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
K.R. Rao Y.R. Krishna P. Venkateswarlu K.B. Rao V.S. Rao G.J.N. Raju S.B. Reddy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(3):283-286
A method is suggested to effect the self absorption correction in a different way to estimate the K X-ray intensity ratios
particularly when heavy ions are used as projectiles. Employing this method, the Kβ/Kα intensity ratios are measured in some 3d shell elements by using Carbon and Nitrogen ions as exciting agents. The Kβ/Kα intensity ratios thus obtained in the present work are compared with the intensity ratios due to some previous authors and
also with Scofield theoretical values.
Received 14 August 2000 and Received in final form 3 January 2001 相似文献