Adiabatic and non-adiabatic corrections to properties of the hydrogen molecular cation and its isotopomers: dissociation energies and bond lengths

A study is presented of adiabatic and non-adiabatic corrections to the dissociation energies and bond lengths of H⁺ ₂, D⁺ ₂ and HD⁺ in vibration-rotation levels of their ground electronic states, with particular attention to isotopic scaling. In previous work (MOSS, R. E., 1999, Molec. Phys., 97, 1) on rotationless levels, an anomalous non-adiabatic correction to the bond length was found for v = 20, N = 0 of HD⁺. Other levels close to dissociation are identified that display anomalous non-adiabatic corrections to the dissociation energies and to the bond lengths. The source of these anomalies is discussed.     

Structural Deformation of CO22+ in Intense Femtosecond Laser Fields

The angular distributions of CO^＋ from the dissociation of CO2^2＋ and CO2^＋ in intense femtosecond laser fields （45 fs, about 5 × 10^15 W/cm^2） are studied at a laser wavelength of 800nm based on the time-of-flight mass spectra of CO^＋ fragment ions. The experimental results show that structural deformation occurs in the charge state of CO2^2＋ and the CO^＋ maintains linear geometrical structure.     

Dissociation Energies of Diatomic Molecules

Molecular dissociation energies of 10 electronic states of alkali molecules of KH, ^7LiD, ^7 LiH, ^6LiH, NaK, NaLi and NaRb are studied using the highest three accurate vibrational energies of each electronic state, and an improved parameter-free analytical formula which is obtained starting from the LeRoy Bernstein vibrational energy expression near the dissociation limit. The results show that as long as the highest three vibrational energies are accurate, the current analytical formula will give accurate theoretical dissociation energies De^theory, which are in excellent agreement with the experimental dissociation energies De^expt.     

HD+2，H+3和D+3与固体相互作用和三体尾流效应

从分子离子H⁺₃及其氘化同位素分子离子D⁺₃和HD⁺₂与超薄固体膜相互作用发生库仑爆炸为基础,分析讨论了H⁺₃,D⁺₃和HD⁺₂三种分子离子的形成机理,根据产物能谱分布,利用库仑爆炸技术确定了同位素分子离子HD⁺₂的结构形式,给出具体核间距数值.并确定在实验中不存在线状结构的HD⁺₂.提出一种三原子分子离子和固体相互作用中尾流效应的处理方式,通过和实验结果做比较发现这是一种非常理想的处理三体尾流效应的模式,并用之进一步确认了HD⁺₂的结构形状.文章对H⁺₃,D⁺₃和HD⁺₂三种分子离子的实验结果做了对比和讨论. 关键词： +₂')" href="#">微团簇HD⁺₂ +₃和D⁺₃')" href="#">H⁺₃和D⁺₃ 库仑爆炸 三体尾流势 团簇结构     

Charge asymmetry and rovibrational excitations of HD+

Average values of the interparticle distances for rovibrationally excited HD⁺ are calculated using a method where the Born–Oppenheimer (BO) approximation is not assumed. The difference between the proton–electron and deuteron–electron distances is used to describe the charge asymmetry in the system. All-particle one-centre explicitly correlated Gaussian functions are used in the calculations of the HD⁺ rovibrational states. In this work, the non-BO method is extended to calculate the rovibrational states corresponding to the total rotational quantum number of two (N = 2). The algorithms for calculating the Hamiltonian and overlap matrix elements, and the matrix elements of the analytical energy gradient determined with respect to the exponential parameters of the Gaussians, are presented. The gradient is employed in the variational optimisation of the parameters, which is key in obtaining very accurate rovibrational energies in the calculations. The algorithm for calculating the average interparticle distances is also shown. The charge asymmetry of HD⁺ near the dissociation limit occurs, as expected, with the electron preferentially being near to the deuteron. The asymmetry for a particular vibrational level increases with rotational excitations. The rovibrational transition energies are also calculated and compared with available experimental data.     

Triatomic wake effect and the determination of the molecular structure of HD2+ from the Coulomb explosion

A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D+ 3 and HD+ 2 while passing through a solid.The wake effects resulting from the reactions of the two similar ions with thin carbon foil are also investigated by using the Coulomb explosion technique.The experimental results are in good agreement with theoretical estimates and the molecular structure of HD+ 2 is determined by using the model.     

两束啁啾脉冲控制下的H+D+光缔合反应研究

从理论上研究了两束啁啾脉冲控制H+D⁺的光缔合反应. 第一束脉冲用来加速碰撞伴的碰撞速度,第二束脉冲用来增加产物HD⁺的产率. 结果表明:第一束脉冲的参数决定了第二束脉冲的优化参数以及产物HD⁺的布居. 产物的布居可以通过调节两束脉冲的延迟时间得到控制. 关键词： 光缔合 +分子')" href="#">HD⁺分子 啁啾脉冲 波包     

Electronic Curves Crossing in Methyl Iodide by Spin--Orbit Ab Initio Calculation

An ab initio investigation of electronic curve crossing in a methyl iodide molecule is carried out using spin-orbit multiconfigurational quasidegenerate perturbation theory. The one-dimensional rigid potential curves and optimized effective curves of low-lying states, including spin-orbit coupling and relativistic effects, are calculated. The spin-orbit electronic curve crossing between ^3Qo＋ and ^1Q1, and the shadow minimum in potential energy curve of ^3Qo＋ at large internuclear distance are found in both sets of the curves according to the present calcu- lations. The crossing position is in the range of Re-1 = 0.2370 3：0.0001 nm. Comparisons with other reports are presented.     

Ionizing Dose Effect of Thermal Oxides Implanted with Si^＋ Ions

Total ionizing dose effects of Si^＋ ion implanted thermal oxides are studied by 10keV x-ray irradiation. Photoluminescence （PL） method is engaged to investigate nanostructures of samples. Ar^＋ implanted samples are also studied by the same way to provide a comparison. The results show that Si^＋ implantation following with high temperature annealing can significantly reduce the radiation induced flatband shift, which is caused by net posi- tive charge accumulation in oxides. This reduction is attributed to the formation of Si nanoscale structures. Ar^＋ implantation is also found to reduce the radiation induced flatband shift, while it is different that the reduction with Si^＋ implantation shows little dependence on implant dose of Ar^＋ ions. This is explained by possible increase of recombination centres.     

Dissociation of molecular hydrogen ions by an IR laser pulse

Dissociation dynamics of the simplest molecular systems, such as H₂ ⁺, D₂ ⁺ and HD⁺ ions, in an intense IR laser field has been investigated by numerical modeling. An n-term approximation has been developed to describe the molecular system dynamics in an intense electromagnetic field. Calculations by the n-term approximation have been compared to an accurate numerical solution of the two-particle problem. The dissociation probability as a function of the frequency and intensity of radiation for different isotopes in a molecular hydrogen ion is discussed. A quasistatic model of molecule dissociation in an IR field has been suggested, and limits of its applicability have been determined. Zh. éksp. Teor. Fiz. 113, 128–143 (January 1998)     

Multimode-Waveguide-Based Optical Power Splitters in Glass

Low-loss glass-based buried multimode waveguides are fabricated by using the field-assisted Ag＋-Na＋ ionexchange technique, and multimode optical power splitters are investigated. The measured loss of the multimode waveguides is lower than 0.1 dB/cm, and the additional loss of the multimode optical power splitters is lower than 1.3 dB under the uniform splitting condition.     

Fragmentation of CO in Femtosecond Laser Fields

Fragmentation of CO in a linearly polarized femtosecond laser field within the intensity order of 10^14 W.cm^-2 at 820nm is investigated experimentally by using velocity mapping technique. According to the observed kinetic energy and angular distributions of different charged fragment ions, fragmentation channels of CO are proposed. The angular distributions provide helpful information for assigning the dissociation channels.     

Ab Initio Calculations of Differential Cross Sections for Single Charge Transfer in ^3He^2＋ ＋ ^4He Collisions

The single charge transfer process in ^3He^2＋ ＋ ^4He collisions is investigated using the quantum-mechanical molecular- orbital close-coupling method, in which the adiabatic potentials and radial couplings are calculated by using the ab initio multireference single- and double-excitation configuration interaction methods. The differential cross sections for the single charge transfer are presented at the laboratorial energies E = 6 keV and lOkeV for the projectile ^3He^2＋. Comparison with the existing data shows that the present results are better in agreement with the experimental measurements than other calculations in the dominant small angle scattering, which is attributed to the accurate calculations of the adiabatic potentials and the radial couplings.     

Kinetic Energy of Trapped Ions Cooled by Buffer Gas

The average kinetic energy of 40 Ca＋ ions is measured by the method of evaporating ions in an rf ion trap. The kinetic energy of the ion 40Ca＋ varies from 0.5eV to 0.2eV with changing buffer gas pressure from 10^-7 mbar to 10^-5 mbar. The Brownian motion model is also introduced to calculate the average kinetic energy of the trapped ions.     

Observation of the v′=8←v=0 vibrational overtone in cold trapped HD+

We report the observation of the hitherto undetected v′=8←v=0 vibrational overtone in trapped HD⁺ molecular ions, sympathetically cooled by laser-cooled Be⁺ ions. The overtone is excited using 782 nm laser radiation, after which HD⁺ ions in v=8 are photodissociated by the 313 nm laser used for Be⁺ cooling. The concomitant loss of HD⁺ is detected by the method of secular excitation (Roth et al. in Phys. Rev. A. 74:040501(R), 2006). We furthermore present details of the experimental setup, and we show that results from spectroscopy of v′=8←v=0 overtones in combination with accurate ab initio calculations may yield a new value for the proton–electron mass ratio with an accuracy of order 1 ppb.     

Luminescent Characteristics of LiSrBO3：Eu3＋ Phosphor for White Light Emitting Diode

LiSrBO3 ：Eu3＋ phosphor is synthesized by a high solid-state reaction method, and its luminescent characteristics are investigated. The emission and excitation spectra of LiSrBO3：Eu3＋ phosphors exhibit that the phosphors can be effectively excited by near ultraviolet （401 nm） and blue （471 nm） light, and emit 615nm red light. The effect of Eua＋ concentration on the emission spectrum of LiSrBO3：Eu3＋ phosphor is studied; the results show that the emission intensity increases with increasing Eu3＋ concentration, and then decreases because of concentration quenching. It reaches the maximum at 3mol%, and the concentration self-quenching mechanism is the dipoledipole interaction according to the Dexter theory. Under the conditions of charge compensation Li＋, Na＋ or K＋ incorporated in LiSrBO3, the luminescent intensities of LiSrBO3 ：Eua＋ phosphor are enhanced.     

Accurate theoretical vibration-rotation energies and transition moments for HD+, HT+, and DT+

In this paper we report a theoretical calculation of vibration-rotation transition wavenumbers and transition moments for HD⁺, HT⁺, and DT⁺ for v, N ≤ 5. The results for HD⁺ agree with the experimental results to within 0.015 cm^?1.     

The influence of Exciting Frequency on N2 and N2+ Vibrational Temperature of Nitrogen Capacitively Coupled Plasma

By using optical emission spectroscopy （OES）, N2 and N2^＋ vibrational temperatures in capacitively coupled plasma discharges with different exciting frequencies are investigated. The vibrational temperatures are acquired by comparing the measured and calculated spectra of selected transitions with a least-square procedure. It is found that N2 and N2^＋ vibrational temperatures almost increase linearly with increasing exciting frequency up to 23 MHz, then increase slowly or even decrease. The pressure corresponding to the maximum point of N2 vibrational temperature decreases with the increasing exciting frequency. These experimental phenomena are attributed to the increasing electron density, whereas the electron temperature decreases with exciting frequency rising.     

A Theoretical Study of Photoabsorption Cross Sections of Na^＋ 2

In the framework of quantum defect theory, we calculate photoabsorption cross sections of Na^＋ 2. Based on our calculations, there is an absorption window in the photoabsorption cross sections of Na^＋ 2. and more than one bump above the absorption window. The calculated photoabsorption cross sections provide an explanation for the abnormal bump in the experimental measurements of Hudson, which is a long-standing experimental puzzle.     

Resonances and chaos in the collinear collision system (He,H 2 + ) and its isotopic variants

The collinear atom-diatom collision system provides one of the simplest instances of chaotic or irregular scattering. Classically, irregular scattering is manifest in the sensitive dependence of post-collision variables on initial conditions, and quantally, in the appearance of a dense spectrum of dynamical resonances. We examine the influence of kinematic factors on such dynamical resonances in collinear (He, H ₂ ⁺ ) collisions by computing the transition state spectra for collinear (He, HD⁺) and (He, DH⁺) collisions using the time-dependent quantum mechanical approach. The nearest neighbor spacing distributionP(s) and the spectral rigidity Δ₃(L) for these resonances suggest that the dynamics is predominantlyirregular for collinear (He, HD⁺) and predominantlyregular for collinear (He, DH⁺). These findings are reinforced by a significantly larger “correlation hole” in ensemble averaged survival probability ≪P(t)≫ values for collinear (He, HD⁺) than for collinear (He,DH⁺). In addition we have also examined measures of classical chaos through the dependence of the final vibrational action,n _f, on the initial vibrational phaseφ _i of the diatom, and Poincaré surfaces-of-section. They show that (He, HD⁺) collisions are partly chaotic over the entire energy range (0–2.78 eV) while (He, DH⁺) collisions, in contrast, are highly regular at collision energies below the classical threshold for reaction. Above the threshold, the scattering remains regular for initial vibrational statesv=0 and 1 of DH⁺.