首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
An algebraic model that describes the internal dynamics of the ionic complexes ArH3+ and ArD3+ in the ground electronic-vibrational state taking into account the torsional motion of the structure of identical hydrogen nuclei is constructed by symmetry-group chain methods. It is important that the correctness of this model is only limited by the correctness of the choice of geometric symmetry of the internal dynamics of the ionic complex.  相似文献   

2.
Using the symmetry group chain methods, the internal dynamics of the simplest carbocation, C2H 3 + , is analyzed under the traditional assumptions that the equilibrium structures of the carbocation are planar and that the nonrigid motion between them is in-plane. This geometry of the internal dynamics is shown to agree with the data of the microwave spectroscopy on the splittings of rotational energy levels caused by the nonrigid motion. Previously, this statement was based on the model that violated the requirement of self-adjointness of operators of physical quantities.  相似文献   

3.
The third continuum of argon from 200 to 270 nm is obtained by electron beam pumping argon. With the front mirror and the rear mirror, the resonator effects are observed at 240 and 220 nm. Compared with the intensity of fluorescence, the intensity near 240 nm increases more than 10 times when the resonator is formed. In order to explain the origin of the continuum, the kinetic model on Ar2+ and Ar22+ ionic excimers pumped by electron beam is built and calculated. Based on the theoretical results, the Ar2+ ionic excimer should be responsible for the continuum around 240 nm.  相似文献   

4.
Absolute cross-sections for electron-impact ionization and dissociation of C2H2+ and C2D2+ have been measured for electron energies ranging from the corresponding thresholds up to 2.5 keV. The animated crossed beams experiment has been used. Light as well as heavy fragment ions that are produced from the ionization and the dissociation of the target have been detected for the first time. The maximum of the cross-section for single ionization is found to be (5.56 ± 0.03)× 10-17 cm2 around 140 eV. Cross-sections for dissociation of C2 H2+ (C2D2+) to ionic products are seen to decrease for two orders of magnitude, from C2D+ (12.6 ± 0.3) × 10-17 cm2 over CH+(9.55 ± 0.06) × 10-17 cm2, C+ (6.66 ± 0.05) × 10-17 cm2, C2+ (5.36 ± 0.27) × 10-17 cm2, H+ (4.73 ± 0.29) × 10-17 cm2 and CH2+ (4.56 ± 0.27) × 10-18 cm2 to H2+ (5.68 ± 0.49) × 10-19 cm2. Absolute cross-sections and threshold energies have been compared with the scarce data available in the literature.  相似文献   

5.
Absolute cross-sections for electron-impact dissociative ionization of C2 H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+ and C2D+ fragments are determined for electron energies ranging from the corresponding threshold to 2.5 keV. Results obtained in a crossed beams experiment are analyzed to estimate the contribution of dissociative ionization to each fragment formation. The dissociative ionization cross sections are seen to decrease for more than an order of magnitude, from CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19± 0.16) × 10-17 cm2, C2D+ (3.94±0.38) × 10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2 and H+ (3.37±0.21) × 10-17 cm2 to CH2+ (2.66±0.14) × 10-18 cm2. Kinetic energy release distributions of fragment ions are also determined from the analysis of the product velocity distribution. Cross section values, threshold energies and kinetic energies are compared with the data available from the literature. Conforming to the scheme used in the study of the dissociative excitation of C2H2+ ( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in a format suitable for their implementation in plasma simulation codes.  相似文献   

6.
We have studied the formation of the molecular ion Rb2+ and the atomic ion Rb+. These are created in laser excited rubidium vapor at the first resonance, 5s–5p and 5p-nl transitions. A theoretical model is applied to this interaction to explain the time evolution and the laser-power dependence of the population density of Rb+ and Rb2+. A set of rate equations which describe: the temporal variation of the population density of the excited states; the atomic ion density; and the electron density, were solved numerically under the experimental conditions of Barbier and Cheret. In their experiment the Rb concentration was 1×1013cm−3 and the laser power was taken to be 50–500 mW at vapor temperature = 450 K. The results showed that the main processes for producing Rb2+ are associative ionization and Hornbeck-Molnar ionization. The calculations have also showed that, the atomic ions Rb+ are formed through the Penning Ionization (PI) and photoionization processes. Moreover, a reasonable agreement between the experimental results and our calculations for the ion currents of the Rb+ and Rb2+ is obtained.   相似文献   

7.
Absolute cross sections for electron-impact single ionization, dissociative excitation and dissociative ionization of the ethynyl radical ion (C2D+)^+) have been measured for electron energies ranging from the corresponding reaction thresholds to 2.5 keV. The animated crossed electron-ion beam experiment is used and results have been obtained for the production of C2D2+, C2+, C2+_2^+ , CD+, C+ and D+. The maximum of the cross section for single ionization is found to be (2.01 ± 0.02) × 10-17 cm2, at the incident electron energy of 105 eV. Absolute total cross sections for the various singly charged fragments production are observed to decrease by a factor of almost three, from the largest cross-section measured for C+, over C2+_2^+ and CD+ down to that of D+. The maxima of the cross sections are obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+, (12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ± 0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+. The smallest cross section is measured to be (1.50 ± 0.04) × 10-18 cm2 for the production of the doubly charged ion C2+. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic energy release distributions of dissociation fragments are seen to extend from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for CD+, 14.2 eV for C+ and 11.2 eV for D+ products.  相似文献   

8.
Absolute transition frequencies of the b 3Π(0u +) - X 1Σg + system of K2 were measured in a molecular beam with Lamb dip absorption spectroscopy applying a frequency comb from a femtosecond pulsed laser. Both, K atoms and K2 molecules are present in the beam and are expected to interact by collisions. The atoms can be deflected optically out of the beam, and thus the collision rate between K atoms and K2 molecules is changed by about an order of magnitude. The molecular transition frequencies for low collisional rate are compared with those for high one. Limits for the collisional frequency shift within the beam are determined.  相似文献   

9.
We study the photoelectron angular distributions (PADs) of diatomic molecule H2 + irradiated by intense laser fields using a nonperturbative scattering theory. We find that the internuclear vector may change the PADs. The PADs have qualitative changes with the increasing of the internuclear distance. The molecular orientation affect the symmetry of the PADs. When the internuclear vector is vertical or parallel to the laser polarization vector, the PADs are four-fold symmetric; for other case the PADs are two-fold symmetric. Due to the modulation effect resulting from the molecular multi-core nature, the size of the jet and the main lobe can be enlarged or reduced. The molecular modulation effect become obvious for large internuclear distance.  相似文献   

10.
We report adiabatic potential energy curves of the Li2 + molecule. Our curves are tabulated according to internuclear distance from 2 a0 to 100 a0. We compare our theoretical results with the ones calculated by other authors and potential energy curves derived from experiments. For the ground state and 17 excited states we calculate spectroscopic parameters and compare them with parameters obtained by other authors. For the first time we present three new minima for 32Σu +, 42Σu + and 22Πg excited states. In our approach we use the configuration interaction method where only the valence electrons of Li atoms are treated explicitly. The core electrons are represented by pseudopotential. All calculations are performed by means of MOLPRO program package.  相似文献   

11.
The anomalous character of threshold properties in the ion-molecule reactions H 2 + + H 2 + → H 3 + + p and H 2 + + H 2 + → H + p + H + p has been theoretically analyzed. It has been shown that these reactions proceed through the formation of the intermediate H 4 ++ complex. Molecules H 2 + in the collision process are described by a chemical model, where the positive charge is concentrated in one of the nuclei. The calculations of the reaction cross sections are in good agreement with the experimental data. It has been shown that the chemical model of the H 2 + molecule can be consistently explained only in terms of dynamic interactions, i.e., polarization forces and van der Waals forces.  相似文献   

12.
Starting fromthe Skyrme interaction f_ together with the volume pairing interaction, we study the g factors for the 21,2+ excitations of 132,134,136Te. The coupling between one- and two-phonon terms in the wave functions of excited states is taken into account within the finite-rank separable approximation. Using the same set of parameters we describe the available experimental data and give the prediction for 136Te, g(21+) = ?0.18 in comparison to +0.32 in the case of 132Te.  相似文献   

13.
14.
Absolute cross-sections have been measured for electron-impact dissociative excitation and ionization of CD2+ leading to formation of CD22+, CD+, C+, D2+ and D+. The animated crossed-beams method is applied in the energy range from the reaction threshold up to 2.5 keV. The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 for CD22+, CD+, C+, D2+ and D+ respectively. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product, which are of significant interest in fusion plasma edge modelling and diagnostics. Conforming to the scheme recently applied in the CD4+ and in the CD3+ articles, the cross-sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic-energy-release distributions are determined for each ionic fragment at selected electron energies.  相似文献   

15.
The electronic structures of the manifold of potential energy surfaces generated in the lower energy range by the interaction of the MgH+(X1Σ+)  cationic molecule with Rb(2S)  neutral atom are obtained over a broad range of Jacobi coordinates from strongly correlated ab initio calculations which use a Multireference (MR) wavefunction within a Complete Active Space (CAS) approach. The relative features of the lowest five surfaces are analyzed in terms of possible collisional outcomes when employed to model the ultracold dynamics of ionic molecular partners.  相似文献   

16.
The integral equations of liquids (RISM) and molecular dynamics method were used to calculate the mean force potential for the SO3 and COO hydrophilic groups and the CH3 hydrophobic group in the acetate, methyl sulfonate, and hydrosulfate anions, which form ion pairs with sodium and potassium cations in water. The carboxyl group selectively binds sodium ions from solutions containing Na+ and K+ ions, in spite of their equal charges, because the potassium ion experiences stronger steric hindrances near this group compared with sodium. The biophysical consequences of the revealed selectivity are discussed.  相似文献   

17.
The general analysis of the rare Bc→Ds *+- decay is presented by using the most general, model independent effective Hamiltonian. The dependencies of the branching ratios and of the longitudinal, normal and transversal polarization asymmetries for ℓ- and the combined asymmetries for ℓ- and ℓ+ on the new Wilson coefficients are investigated. Our analysis shows that the lepton polarization asymmetries are very sensitive to the scalar and tensor type interactions, which will be very useful in looking for new physics beyond the standard model.  相似文献   

18.
Absolute cross sections for electron-impact dissociative excitation and ionization of CD+ 4 leading to formation of ionic products (CD2+ 4, CD+ 3, CD+ 2, CD+, C+, D+ 3, D+ 2, and D+) have been measured. The animated crossed-beams method is applied in the energy range from the reaction threshold up to 2.5 keV. Around 100 eV, the maximum cross sections are found to be (3.8±0.2) ×10-19 cm2,  cm2, (7.1±0.8) ×10-17 cm2, (9.0±0.8) × 10-17 cm2 and (3.7±0.4) ×10-17 cm2 for the heavy carbonaceous ions CD2+ 4, CD+ 3, CD+ 2, CD+ and C+ respectively. For the light fragments, D+ 3, D+ 2, and D+, the cross sections around the maximum are found to be (5.0±0.6) ×10-19 cm2, (1.7± 0.2) ×10-17 cm2 and (10.6±1.0) ×10-17 cm2, respectively. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. The analysis of ionic product velocity distributions allows determination of the kinetic energy release distributions which are seen to extend from 0 to 9 eV for heavy fragments, and up to 14 eV for light ones. The comparison of present energy thresholds and kinetic energy release with available published data gives information about states contributing to the observed processes. Individual contributions for dissociative excitation and dissociative ionization are determined for each detected product. A complete database including cross sections and energies is compiled for use in fusion application.  相似文献   

19.
A. Oueslati 《Ionics》2017,23(4):857-867
A lithium yttrium diphosphate LiYP2O7 was prepared by a solid-state reaction method. Rietveld refinement of the X-ray diffraction pattern suggests the formation of the single phase desired compound with monoclinic structure at room temperature. The infrared and Raman spectrum of this compound was interpreted on the basis of P2O7 4? vibrations. The AC conductivity was measured in the frequency range from 100 to 106 Hz and temperatures between 473 and 673 K using impedance spectroscopy technique. The obtained results were analyzed by fitting the experimental data to the equivalent circuit model. The Cole–Cole diagram determined complex impedance for different temperatures. The angular frequency dependence of the AC conductivity is found to obey Jonscher’s relation. The temperature dependence of σ AC could be described in terms of Arrhenius relation with two activation energies, 0.87 eV in region I and 1.36 eV in region II. The study of temperature variation of the exponent(s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the correlated barrier hopping (CBH) model in region I (T < 540 K) and non-overlapping small polaron tunneling (NSPT) model in region II (T > 540 K). The near value of activation energies obtained from the equivalent circuit and DC conductivity confirms that the transport is through ion hopping mechanism dominated by the motion of the Li+ ion in the structure of the investigated material.  相似文献   

20.
The electronic structure, the equilibrium geometric configuration, and the charge distribution are calculated for the positive endofullerene ion [Ce@C60]+. It is shown that the equilibrium distance from the Ce atom to each of the six nearest C atoms almost coincides with the sum of the cerium ionic radius and the carbon atomic radius. The spectrum of electronic transitions in the visible and UV regions is presented.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号