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1.
The neutralization of H− ions in collisions with fast, multiply charged ions is considered in the parameter region where the Born approximation applies.
An analytical formula is obtained for the H− neutralization cross section in such collisions.
Zh. Tekh. Fiz. 69, 1–4 (July 1999) 相似文献
2.
The scattering of quasichanneled particles on atomic chains and planes is studied by computer simulation for the crystals of chemical compounds. It is shown that quasichanneling is the specific regime of ion motion in the lattice. Its main features are: (1) a sharp increase of the backscattering probability; (2) transition of the ions from the quasichanneled component into a random one; (3) high sensitivity to the structure and the composition of the atomic “chain”; (4) dependence on the value and the direction of the atomic displacements. 相似文献
3.
We have detected excess micromotion of trapped ions by modulating the trapping voltage. This radio-frequency (rf) modulation
induces parametric resonance and excites secular motion of the trapped ions when they possess excess motion. This technique
has been applied to laser-cooled ions in a linear rf trap and it provides optimum values for compensating the trapping field.
We found that the technique has sensitivity equal to or greater than the conventional method for detecting excess micromotion.
Because any laser propagation direction can be used, this method is expected to be applied to surface-electrode traps. 相似文献
4.
The predissociation or particle emitting decay rates of muonic molecular ions3He dµ and4He dµ are estimated by means of the complex rotation method. We use a highly accurate variational three-bodyP-wave function based on random-tempered Slater-type exponential expansion. A resonance eigenvalue ofE=–48.420 89 eV and =0.348 × 10–3 eV for the3He dµ ion and a resonance eigenvalue ofE=–58.225 303 eV and =0.118 × 10–3 eV for the4He dµ ion have been obtained. These results are in a good agreement with the ones previously obtained by Kino and Kamimura by scattering calculation with the non-adiabatic coupled-rearrangement-channel method. 相似文献
5.
Zn-doped β-tricalcium phosphate (β-TCP) is synthesized by the solid-state reaction method. The substitution mechanism of Zn ions in β-TCP synthesized here is investigated by carrying out a combination of near-edge X-ray absorption fine structure (NEXAFS) measurements and first-principles calculations. From the results of the present study, the substitution site for Zn ions in β-TCP is successfully determined. 相似文献
6.
《Surface science》1986,173(1):234-244
Electron-stimulated desorption (ESD) of positive ions (H+, O+, +OH, F+ and Cl+) from the Si- and C-terminated surfaces of hexagonal α-SiC has been observed for electron energies in the 5–105 eV range. Comparison of these results with those for the ESD of the same ions from the surfaces of Si and condensed hydrocarbons leads to a model for the H+, +OH, F+ and Cl+ threshold desorption process based on transitions from deep valence Si and C “s-like” levels to states in the conduction band, followed by Auger decay to form a localized multiple valence-hole configuration. O+ desorption, on the other hand, is initiated by O 2s ionization. Evidence is found for a strong dependence of the F+ threshold on the local chemical bonding. The results indicate that the thresholds for ESD of these ions from SiC are determined more by the electronic excitation of the substrate than by direct excitation of the adsorbate bond. 相似文献
7.
Radu Cazan Christopher Geppert Wilfried N?rtersh?user Rodolfo Sánchez 《Hyperfine Interactions》2010,196(1-3):177-189
Sympathetic cooling by laser cooled Mg ions has been proposed as a method for fast cooling of highly charged ions to a very low temperature. The paper describes the construction of the solid state laser system at 279.63 nm required for laser cooling of the Mg ions. The laser system is composed of a fiber laser at 1,118.54 nm and two successive second harmonic generation (SHG) ring cavities for frequency quadrupling. In the first SHG cavity, non-critical phase matching of a lithium triborate (LBO) crystal is used for doubling from 1,118.54 to 559.27 nm. The second SHG cavity uses critical phase matching of a β-barium borate (BBO) crystal for doubling from 559.27 to 279.63 nm. With the aid of Boyd–Kleinmann theory, optimum experimental parameters are calculated and used for an efficient SHG. Besides this, the paper intends to be a shortcut for practical applications of the Boyd–Kleinmann theory for SHG. 相似文献
8.
Adsorption of sodium ions and hydrated sodium ions on a hydrophobic graphite surface via cation-π interactions
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Using density functional theory computation, we show that sodium ions and hydrated sodium ions can be strongly adsorbed onto a hydrophobic graphite surface via cation-π interactions. The key to this cation-π interaction is the coupling of the delocalized π states of graphite and the empty orbitals of sodium ions. This finding implies that the property of the graphite surface is extremely dependent on the existence of the ions on the surface, suggesting that the hydrophobic property of the graphite surface may be affected by the existence of the sodium ions. 相似文献
9.
E. Z. Utyanskaya B. V. Lidskii M. G. Neigauz A. E. Shilov 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(6):884-895
It was shown earlier that the hydrolysis of the (CuATP2−)2 dimeric complex to CuADP− and inorganic phosphate P
i
was an irreversible reaction. The main intermediate hydrolysis product, the formation of which should be taken into account
at comparatively early hydrolysis stages, was the IntK pentacovalent intermediate. It was formed in parallel with hydrolysis
to CuADP− and P
i
through the common intermediate product (CuATP2−)2OH− — DOH−. We studied the influence of the addition of various concentrations of Mg2+ ions to the reaction mixture at pH 7.1–7.2, a range for which the kinetics of hydrolysis is sensitive to the rate constants
of deactivation of DOH− active centers (conjugated with CuADP− formation and occurring via the formation of IntK). The conversion of ATP above which stationary hydrolysis regime was observed
decreased as the concentration of Mg2+ grew. The DOH−
$
\underset{{OH^ - }}{\overset{{OH^ - }}{\longleftrightarrow}}$
\underset{{OH^ - }}{\overset{{OH^ - }}{\longleftrightarrow}}
IntK equilibrium according to the conversion of ATP was established more rapidly, and it was to a greater extent shifted toward
IntK. It was assumed that hydrated Mg2+ linked as a second metal ion with ATP β and γ phosphate groups hydrated IntK much stronger than DOH−. The Cu · OH2 · AMP complex played the role of a common acid catalyst and hydrated DOH− better than Mg2+ · OH2. The selective hydration of DOH− by the CuOH2 · AMP complex at early hydrolysis stages directed the process toward the formation of IntK, which caused the appearance of
an induction period in the formation of CuADP−. 相似文献
10.
B. Furmann G. Szawiola A. Jarosz A. Krzykowski D. Stefanska J. Dembczynski 《Hyperfine Interactions》2010,196(1-3):61-69
Various experimental methods, used in Chair of Quantum Engineering and Metrology for determination of the hyperfine structure of electronic levels in lanthanides atoms and ions, are presented. In turn the spectroscopic methods on an atomic beam (laser induced fluorescence and laser-rf double resonance ABMR-LIRF), laser-rf double resonance in a Paul trap and spectroscopic methods in a hollow cathode discharge (optogalvanic detection and laser induced fluorescence) are presented. Each method has been characterized with its potential accuracy and domain of application. The results achieved for the atoms and the ions of lanthanum, praseodymium, neodymium and europium have been published in numerous articles (compiled in the reference list). 相似文献
11.
Close-coupling calculations based on an R-matrix formalism are
performed for the 1s--2p resonance photoionizations from the
low-lying states of boron-like carbon ions. The resonance energies,
widths and oscillator strengths of 1s-2p core excitations are
determined by analysing the calculated photoionization cross
sections. Our calculations are in
reasonable agreement with the experimental and
theoretical results presented by other authors. The present numerical values may
help to analyse the astrophysical and laboratory plasmas. 相似文献
12.
A program is developed to calculate the ion energy distributions (IEDs) of Ar2^+ making use of a simplified kinetic model with a combination of Monte Carlo method. Several coefficients are used to realize good match between the calculated and measured results. Some important assumptions are confirmed: argon excimer ions have short lifetime, hence they are formed in a short range before the collecting electrode. The excimer ions that encounter collisions will be discarded because they turn to other ion species after they collide with argon atoms. From the calculated results some plasma parameters such as the cross section or neutral density in discharge could be evaluated. 相似文献
13.
Ronghua Wan Zhiguo Song Yongjin Li Qun Liu Yuting Zhou Jianbei Qiu Zhengwen Yang Zhaoyi Yin Qi Wang Dacheng Zhou 《中国光学快报(英文版)》2014,12(11):111601-64
We study the influence of alkali oxides on the near-infrared(NIR)-emitting thermal stability of Bi-doped R2O–Si O2–B2O3–Al2O3(R = Li, Na, K) glasses below Tg. Results show that undergoing heat treatment, remarkable luminescence quenching occurs for the glasses containing Na2 O and K2 O due to the formation of Bi metallic colloids, whereas the glass with Li2 O shows much better thermal stability. These changes can be understood by the tendency of modifier cations with lower mobility and higher tightness network to restrain the transport of Bi-related NIR-emitting centers. The results provide a scientific reference for composition design of Bi-doped optical fiber. 相似文献
14.
《中国光学快报(英文版)》2008,(6)
We use an electrostatic model to study the average kinetic energy of ions ejected from the pure Coulomb explosions of methane clusters(CA_4)_n(light atom A=H and D).It is found that the ratio of the average kinetic energy of the ions to their initial average electrostatic potential energy is irrelevant to the cluster size.This finding implies that as long as the ratio is given,the average kinetic energies of the ions can be simply estimated from their initial average electrostatic potential energies,rather than from the time- consuming simulations.The ratios for the different charge states of carbon ions are presented. 相似文献
15.
The molecular structures and spectroscopic constants of the ground electronic states of LiCl? and LiBr? are investigated with the coupled-cluster method. To improve the accuracy of our calculations, we have employed the extrapolation schemes as well as corrections of the core–valence correlation and scalar relativistic effect. The equilibrium parameters, potential energy curves, force constants, vibrational energy levels and spectroscopic parameters of both molecular ions are derived, in which those of LiBr? are reported for the first time. The electron affinities and vertical detachment energies of neutral and anionic LiCl and LiBr are also evaluated. 相似文献
16.
The characteristic angles and cross sections for a (\mathop 1- 0) + (\mathop 1- 1)(\mathop 1\limits^ - 0) + (\mathop 1\limits^ - 1) reaction in which H− atoms with an energy of 0.1–10 000 MeV lose electrons when scattered on C, N, or O atoms were calculated for the relativistic case of the Bethe scattering theory. The cross sections for N2, O2, and CO2 molecular targets were obtained using the additivity rule. The results presented are compared with known experimental and theoretical data. 相似文献
17.
R. K. Gubaidullin 《Russian Physics Journal》1991,34(1):1-4
The dynamics of Fe3+ ions in bipyramidal 2b positions of a type M hexaferrite are studied on single-crystal and polycrystalline SrFe6Ga6O19 samples in the paramagnetic temperature range. We show that when the angle between the c axis of the crystal and the direction of -ray emission varies from 0 to 32 the area under the resonance lines corresponding to Fe3+ ions in 2b positions increases by a factor of roughly 1.5. The effect is more pronounced upon passing from a single-crystal sample (=0) to a polycrystalline sample. A comparison of the line intensities under different experimental conditions served as a basis for an evaluation of the difference between the mean-square displacements of the Fe3+ ions in 2b positions along the c axis in the perpendicular plane.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 5–8, January, 1991. 相似文献
18.
Glasses in the system 0.1CuO-(x-0.1)PbO-(1-x)B2O3 (0.3≤ x ≤ 0.7) were synthesized by using the melt quench technique. A number of studies such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier-transform infrared (FTIR) and Raman spectroscopy, electron paramagnetic resonance (EPR) and dielectric properties (viz., dielectric constant ??, dielectric loss and ac conductivity σac) are employed to characterize the glasses. The amorphous nature of the glasses was confirmed using XRD while the glass transition temperature (Tg) of glass samples have been estimated from DSC investigation and found that the Tg decreases with increasing PbO content. Raman and FTIR spectroscopy reveals that when increasing lead ions, the tetrahedral [BO4] units are gradually replaced by trigonal [BO3] units. The EPR study leads to determine the local site of Cu2+ ions and its transformation with the Pb content in the studied glasses. 相似文献
19.
S.J. Haralkar R.H. Kadam S.S More Sagar E. Shirsath M.L. Mane Swati Patil D.R. Mane 《Physica B: Condensed Matter》2012,407(21):4338-4346
The effect of Cr3+ substitution in Mg–Zn ferrite, with a chemical formula Mg0.5Zn0.5CrxFe2−xO4 (x=0.0–1.0), synthesized by a sol–gel auto-combustion reaction is presented in this paper. The resultant powders were investigated by various techniques, including X-ray diffractometry (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), vibrating sample magnetometry (VSM), and DC resistivity. The XRD pattern revealed that the cubic spinel structure is maintained for the all the compositions. The particle sizes measured from XRD and TEM are in good agreement with each other. The cation distribution suggests that Mg2+, Cr3+ and Fe3+ have strong preference towards octahedral B-site. The theoretical lattice constant and experimental lattice constant match each other very well. The IR analysis supports the presently accepted cation distribution. The saturation magnetization decreases linearly with increasing Cr3+ content. Curie temperatures are obtained by the Laoria and AC susceptibility techniques. The dc resistivity has been investigated as a function of temperature and composition. 相似文献
20.
We study the dynamics of a trapped ion placed at an antinode of the standing wave inside a high finesse cavity with consideration of the second sideband excitation between the ionic internal levels and the light field. We investigate the entanglement of the three subsystems embodying the ionic internal levels, the vibrational mode of the ion and the cavity field. 相似文献