【摘要】 在超快强激光应用中,尤其是激光聚变研究,SiO2作为光学元件的主要成分,而光学元件是由无定型二氧化硅组成的,基于无定型二氧化硅结构的复杂性,在理论研究中常常用团簇结构代替无定型结构,而且光学元件在损伤过程中往往会产生各种各样的二氧化硅团簇。因此,基于含时密度泛函理论研究激光脉冲与团簇(SiO2)n(n=6,14)相互作用对二氧化硅玻璃的损伤动力学过程的研究具有很好的应用价值。研究表明,当脉冲激光作用在团簇时,Si—O键长被拉长,激光削弱了Si—O共价键强度,Si—O键逐渐断裂,最终导致整个团簇(SiO2)n结构坍塌而破坏;随激光强度增加,Si—O键首先被破坏的时间缩短;同时飞秒激光诱导电荷密度变化,与飞秒激光脉冲衰退的痕迹一致。更多还原

【Abstract】 In the applications of ultrafast intense laser fields,especially for inertial confinement fusion(ICF)experiments,the major ingredient of optical elements is silica dioxide.Unfortunately,optical elements are made up with amorphous silica dioxide whose structure is very complicated.Because of the difficulties in building structures of amorphous silica,silica dioxide clusters were usually taken as amorphous silica.And the optical elements often produce a variety of silica clusters during the damage process.So it is very necessary to investigate the silica glass damages induced by ultrafast intense laser based on time dependent density functional theory.It is found that when a pulsed laser acts on clusters,the lengths of Si—O bond are increased and laser weakens the strength of covalent bonds of Si—O bond,leading to the gradual breaking of the Si—O bond.Finally,the structures of clusters(SiO2)n(n=6,14)are damaged.With the laser strength enhancing,the Si—O bonds are firstly broken in a shorter time.Meanwhile the charge densities induced by the femtosecond laser also catch variation according with laser degenerating trail.更多还原