高电荷态离子与原子碰撞过程的密耦理论研究

项目名称： 高电荷态离子与原子碰撞过程的密耦理论研究

项目编号： No.10804008

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 王菲

作者单位： 北京理工大学

项目金额： 17万元

中文摘要： 本项目采用双中心原子轨道密耦方法结合模型势理论，研究类氦、类氢等电子系列及裸离子系列与处在基态或激发态的氦原子、锂原子碰撞的俘获、电离截面，及碰撞产生的激发态形成规律和机制，首次将模型势方法拓展应用于类氢等电子系列与氦原子碰撞的研究，对碰撞电荷转移过程随入射离子电荷态的变化规律，以及等电子系列碰撞截面随核电荷数Z的变化规律进行了分析。对于靶原子氦处于激发态1s3d的碰撞，我们发现对于不同的主量子数n，大部分角量子态的单电子俘获截面符合统计分布，而低能态的角量子态则接近二项式分布，与天体光谱研究中所得有关碰撞激发态产生规律的结论相符。迄今国际上对高电荷态离子与原子碰撞主要是对靶原子处在基态的碰撞研究，靶原子处在激发态乃至高里德伯态的理论和实验研究都很少，我们的研究对今后的理论和实验研究都是十分有价值的。我们采用独立粒子近似，初步分析了C和O裸离子与He原子碰撞的双电子双步转移截面。本项目还基于第一性原理，结合分子轨道密耦方法获得的诱导偶极矩和势能面，研究了天体大气中H2-H2，H2-He体系的碰撞诱导吸收谱和大气不透明度。我们的结果对天体光谱和等离子体物理等具有十分重要的学术和应用价值。

中文关键词： 密耦方法;激发态;电荷转移;碰撞诱导吸收;天体光谱

英文摘要： The two-centre atomic orbital close-coupling calculations are carried out for the cross sections of single electron capture and single ionization in collisions between He-like, H-like and bare ions with He atom or Li atom. The relative importance of single ionization (SI) to single capture (SC) are investigated for these systems. The cross sections of double electrons capture in two-step process are also explored by using atomic orbital close-coupling method based on the independent electron approximation. Agreement with earlier theoretical work and laboratory measurements, where these exist, is reasonable. The partial electron capture cross sections for different projectiles indicate that the electron on the target He atom tends to be captured by the projectile into its lower orbital of the outer shell with the decreasing projectile charge. The partial electron capture cross sections for collisions involving excited target He atom indicate that, corresponding with the astrophysical conclusion, most of the l-levels are populated statistically for energies greater than 10 keV, and some distributions of lower n at low collision energy show a trend close to the binomial distribution. The first principles calculations are carried out for the collisional-induced absorption by H2 pairs and H2-He in cool star atmospheres based on the interaction-induced dipole and potential energy surfaces of H2 pairs from ab initio calculations. The infrared absorption spectra of dense gas in "cool" star atmospheres are computed at temperature up to thousands of kelvin by including higher order dipole components. These available data should be helpful for studying the astrophysical spectrum and plasma physics in future experiments.

英文关键词： close-coupling method; excited target atom;electron capture; collisional-induced absorption;astrophysical spectrum