Ion-Beam-Induced Luminescence of LiF Using Negative Ions

Negative ion-beam-induced luminescence(IBIL) measurements of a pure LiF crystal using 20 keV H~-are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission bands are observed in the IBIL spectra and the evolvement mechanisms of the corresponding centers are identified. The difference between the IBIL measurements using positive ions and negative ions is that the intensities of luminescence centers can reach the maxima at lower fluences under negative-ion irradiation due to free charge accumulation.     

Spectroscopy of Molecular Ions

Abstract

Traditionally, molecular ions have been studied by mass spectrometers or ion-counting techniques. The great sensitivity and versatility of these techniques are clearly attested to by the vast amount of mass spectrometric literature. However, it is equally true that mass spectroscopy has its limitations; basically, it provides one only with a charge-to-mass ratio for an ion. Obviously, all quantum state information is lost, particularly the vibrational and rotational, and usually even the electronic distributions of the ions. Similarly, no structural information such as bond lengths and angles is obtained. Indeed, in some cases the information obtained is so slight that one cannot even write a structural formula for the ion or distinguish between different chemical isomers.     

Infrared Spectra of Negative Ions of Amides

Abstract

The anionic derivatives of a series aliphatic, arylaliphatic and aromatic compounds containing amide group were investigated by means of infrared spectroscopy. The stretching vibration frequencies of the amide C=O, the ketone C=O and the N-C(Ph) in the N-anions of the studied compounds were assigncd: the amide C=O shifts 76-180 cm^?1 downward depending on the substituents; the band intensity increases 2.5-3 times. It was found an excellent correlation between the carbonyl stretching vibration frequencies of the studied N-anions with the Hamrnett CJ constants of the substituents.     

Generation and Fragmentation of Phthalide Derivative Negative Ions

Technical Physics - Molecules of diphenylphthalide and 3,3-diphenylphthalide-4′,4′-dicarbonic acid have been studied using the method of dissociative electron capture negative ion mass...     

Negative Ions in a Glow Discharge of Tetrafluoromethane

The Langmuir — probe measurements in a CF₄ — glow discharge reveal a large number of negative ions (10¹⁰ cm^?3) in the plasma between the planar C-electrodes. Under special conditions the density of them exceeds the electron density at several orders of magnitude and sustains a quasi — electron free plasma. The ratio depends on the residence time of the molecular gas in the discharge reactor. It is due to dissociative electron attachment to highly molecular gas components arising from the plasmachemical conversion of CF₄. F^? and CF₃^? are the most important negative ions.     

Electrostatic Ion-Cyclotron Waves in a Plasma with Negative Ions

The dispersion relation for electrostatic ion-cyclotron (EIC) waves in a plasma containing a fraction of negative ions is derived from the fluid picture. Two wave modes are generally possible. Some of their features are investigated.     

Spectroscopic Properties of Gas-Phase Molecular Ions

Abstract

Ions have long been known or suspected to play a major role in various physical and biological phenomena. The majority of these phenomena occur in condensed phases; e.g., electrical conductivity, melting points, Lewis acid-base behavior, and the sodium pump in active transport across membranes—the list could go on ad infinitum.     

Ion-Acoustic Solitary Waves in Multicomponent Plasmas with Negative Ions

By using the perturbation technique, a Kortewege-de-Vries (K-dV) equation for a multicomponent plasma with negative ions and isothermal electrons has been derived. We have discussed the stationary solutions of K-dV equation and it has shown that in the presece of multiple ions, the amplitude of solitons exhibits interesting behaviour, especiallY when the negative ions are present.     

频率含时谐振子运动的双波描述

应用双波函数定义频率含量谐振子的量子状态,频率含时谐振子的运动得到更完整的描述,双波描述的经典极限与经典力学结果相一致。     

Oscillations of Magnetized Dust Grains in Plasma Sheath with Negative Ions

The oscillations of a single magnetized dust grain in electronegative plasma sheath are investigated taking into account the existence of an external magnetic field. The influence of the content of negative ions and the magnetic field intensity on the properties of the dust vibration is analysed. The result shows that the existence of the negative ions in plasma reduces the dust oscillation frequency and drops the equilibrium position of dust, whereas the magnetic field raises the equilibrium position and also reduces the dust oscillation frequency on the condition considered.     

Propagation of Multidimensional Ion-Acoustic Waves in Multicomponent Plasmas with Negative Ions

We made an attempt to study the propagation of multidimensional ion-acoustic waves in multicomponent plasmas that include negative ions by deriving a Kodomtsev-Petviashvili (K-P) equation. The negative ions, as expected, introduce the precursor on the propagation because of which the need arises to derive a modified K-P equation with higher order non-linearity. We have examined a number of solitons like waves and supported the results by numerical simulation. The results reveal the existence of compressive and rarefactive solitary waves which are comparable with those of one-dimensional solitary waves in plasmas with negative ions except that multidimensional propagation of ion-acoustic waves is more involved than unidirectional propagation.     

Competition Between Two Excitation-dissociation Channels for Molecular Ions

建立了三原子分子离子XYZ+(XY2+)解离产生多种离子产物时Eα和Eβ两个解离通道之间竞争的理论模型. 实验测量出碎片产物分支比和对两束解离光光强比的依赖关系后,由理论公式对数据进行拟合获得拟合参数,可以计算出两个激发解离通道α和β的激发截面分支比.     

Lattice Wave of Magnetized Spherical Dust in Radio-Frequency Sheath with Negative Ions

Lattice wave of magnetized spherical dust in radio-frequency sheath with negative ions is investigated. The dispersion relation of two-dimensional hexagonal lattice horizontal wave and the influence of negative ions and magnetic field intensity on the wave are also investigated. The results show that for two-dimensional hexagonal horizontal lattice wave, negative ions reduce the wave frequency at the range of long-wavelength, whereas raising the wave frequency at the range of short-wavelength and magnetic field contributes to dropping the wave frequency a little.     

Molecular Ions and Nanoparticles in RF and AC Traps

Hyperfine Interactions - This report summarizes recent advances in using innovative storage devices based on inhomogeneous, time-dependent electric fields. Electrode arrangements include...     

重离子束注入与生物体的相互作用及遗传诱变的分子机制

低能重离子与生物体系相互作用及其生物诱变效应的应用研究在我国率先兴起， 并在应用中取得了很大的成就。 介绍了重离子注入与生物有机体的相互作用及其主要的生物学效应， 包括细胞染色体水平、 生理生化效应， 以及对DNA损伤修复、 基因表达、 甲基化修饰的影响。 总结了离子注入诱变的分子遗传学机理的相关研究。 同时分析、 比较讨论了高能与低能离子、 离子束与射线的生物学效应的异同。 提出了离子注入今后的研究方向， 特别指出了离子注入对生物基因表达影响研究的重要性。 As a new mutagenesis technique, low energy heavy ion implantation started in China for the study of interaction effect between incident ions and organism, and great achievements have been obtained in crop breeding. The article reviewed the main biological effects induced by heavy ion implantation, including physiology, biochemistry and genetics effects, on levels of cell and chromosome, gene expression, DNA methylation, DNA damage and reparation etc. It compared the differences in mutagenesis for organism by high energy and low energy ion implantation, as well as γ ray radiaiton. Future investigation topics were proposed, the emphasis of researches in future was pointed out, i.e., the molecular mechanism and effects of gene differential expression of organism treated by ion implantation.     

Korteweg-De Vries Equation for Non-Linear Ion-Acoustic Waves in a Plasma with Negative Ions

The theoretical analysis, based on the perturbation technique, of ion-acoustic waves in the vicinity of a Korteweg-de Vries (K-dV) equation derived in a plasma with some negative ions has been made. The investigation shows that the negative ions in plasma with isothermal electrons introduced a critical concentration at which the ion-acoustic wave plays an important role of wave-breaking and forming a precursor while the plasma with non-isothermal electrons has no such singular behaviour of the wave. These two distinct features of ion waves lead to an overall different approach of present study of ion-waves. A distinct feature of non-uniform transition from the nonisothermal case to isothermal case has been shown. Few particular plasma models have been chosen to show the characteristics behaviour of the ion-waves existing in different cases.