Theoretical Study On Affinity Energy And Radius Of Negative Ion And Experimental Study On The Collision Process Of CO_2

This thesis mainly includes the following three research work:I. The the-oretical calculation about affinities and radii of negative ions. II. The study about the relative ionization and dissociation cross sections of the CO2molecule under the impact of negative ions H-, C-, and O-. III. The experimental analysis about (2s1/22p1/22p3/22)5/2—(2s22p1/22p3/2)3/2X-ray transition in the N-like208Pb75+and the theoretical calculation about the transition energies of the (2s1/22p1/22p3/22)5/2-(2s22p1/22p3/2)3/2lines in N-like ions from Sn(Z=50) through U(Z=92).Negative ions play an important role in a number of areas. The studies of negative ions are very important in electron correlation theory, and are also of great importance in plasma physics, ionosphere physics, astrophysics and flame chemistry. About negative ion, we carry out the following work:I. The affinity and radius are two important parameters of negative ion. The study about affinities and radii are important to the theoretical and experimental research in negative ions, and can also provide important basis to the electron correlation theory and collision dynamics. At present, information about the strict quantum mechanical calculations in the theoretical study of collision processes of anions with molecules and atoms is lacking. Some semi-empirical formulas based on the scaling model approach are often used to calculate the cross sections. The electron affinities and radii of anions play an important role in the scaling model approach. However, there is no accurate data about radii of negative ions. The radii of atoms are usually used to replace the ones of anions. Systematic theoretical calculations based on the multi-configuration Dirae-Hartree-Fock method have been carried out for the electron affinities of anions of the elements of group III-VII. At the same time, we calculate the radii of negative ions with the different definitions. The work about affinities of negative ions have been published in Journal of Physics B.II. The research in negative ion-gas collisions can be carried out from the following two aspects:(1). Study the detachment cross section of negative, which has been developed very well until now;(2). Study the ionization and dissociation cross section of gas target, which is done rarely. However, the ionization and dissociation cross section data for gas, especially for atmospheric molecules, are of practical importance in various fields, such as, in fusion-edge plasma diagnostics; gas discharge; planetary-, stellar-, and cometary atmospheres; radiation chemistry; and mass spectrometry and in modeling radiation effects on materials. To do the above research very well, we set up an experimental platform which is used to measured the ionization and dissociation cross sections of gas in the collision of the negative ions with gas. The setup contains the beam pipe, time-of-flight mass spectrometer, position sensitive detector and anode detector with their signal acquisition circuit, gas injection system, electrostatic deflection system, and data acquisition system. After that, we measured the ionization and dissociation cross sections of CO2in the collision with H-, C-, and O-. As far as we know, this is the first data for the ionization and dissociation cross section of CO2in the collision with negative ions. This part of the work has been published in Physics Review A.Additionally, in order to support the work in our group, we performed the analysis about the X-ray transition (2s1/2p1/222p3/22)5/2-(2s22p1/22p3/2)3/2in the N-like208Pb75+. At the same time, combining with the experimental work, we al-so calculated the transition energies of the (2s1/22p1/22p3/22)(2s22p1/2p3/2)3/2lines in N-like ions from Sn(Z=50) through U(Z=92) in theory. The calcula-tions are also compared with the available experimental results. The differences between the measured values and our theoretical results are around1eV. The research of high charge ions is nowadays one of the emerging research direction-s in plasma physics. Precise determination of the accurate structure of highly charged ions is very helpful in testing the atomic structure calculations, especial-ly the quantum-electrodynamics(QED) theory. This part of the work has been published in Journal of Physics B.