已收录 273079 条政策
 政策提纲
  • 暂无提纲
Radiation effects from first principles : the role of excitons in electronic-excited processes.
[摘要] Electron-hole pairs, or excitons, are created within materials upon optical excitation or irradiation with X-rays/charged particles. The ability to control and predict the role of excitons in these energetically-induced processes would have a tremendous impact on understanding the effects of radiation on materials. In this report, the excitonic effects in large cycloparaphenylene carbon structures are investigated using various first-principles methods. These structures are particularly interesting since they allow a study of size-scaling properties of excitons in a prototypical semi-conducting material. In order to understand these properties, electron-hole transition density matrices and exciton binding energies were analyzed as a function of size. The transition density matrices allow a global view of electronic coherence during an electronic excitation, and the exciton binding energies give a quantitative measure of electron-hole interaction energies in these structures. Based on overall trends in exciton binding energies and their spatial delocalization, we find that excitonic effects play a vital role in understanding the unique photoinduced dynamics in these systems.
[发布日期] 2009-09-01 [发布机构] 
[效力级别]  [学科分类] 物理(综合)
[关键词] CARBON;EXCITATION;EXCITONS;IRRADIATION;MATRICES;RADIATION EFFECTS;RADIATIONS Excitation.;Matter-Effect of radiation on.;Radiation effects. [时效性] 
   浏览次数:26      统一登录查看全文      激活码登录查看全文