Study On The Adsorption Of Defect At Silica Surface

Fused silica is the most widely used optical materials in large high-power laser systems,which is often used in large-scale lasers with inertial confinement fusion. Laser irradiation will result in Laser -induced injuries such as densification,melting, spraying, cracks and pits.As a result, the optical transmission properties of materials decreased significantly. In order to improve the anti-laser damage ability of the fused silica, in addition to improving the level of processing and manufacturing technology of fused silica, laser pretreatment, plasma etching and HF etching are used to reduce or eliminate all kinds of defects, they will help to improve the resistance of fused silica to damage the purpose. The various particle groups produced during the pickling process inevitably interact with the fused silica surface / subsurface,affecting the properties of the fused silica device. Therefore,it is very important to study the reaction mechanism between the fused silica surface and the particles,which is helpful for improving the service life of fused silica laser transmission devices. In this paper, the reaction of the surface that contains NBOHC and E 'defects with halogen particles (F, Cl)was studied systematically by the first-principles method of time-dependent density functional theory (TDDFT). Work includes:(1) The silica surface model and the construction of defects. The classical molecular dynamics and ab initio molecular dynamics simulations were used to construct the surface, the atomistic details of the surface region were analyzed using statistics and bond angles and the surface model was judged to be reasonable.(2) The reaction of the surface containing NBOHC defects with the halogen particles. The reaction of NBOHC-deficient surfaces with F-particles and Cl-particles was calculated and compared, respectively. It is concluded that the F particles are more likely to adsorb to the defect surface than to the Cl particles due to the specific analysis of the structure,the adsorption energy, the electronic state density and the bader charge analysis.(3) The reaction of the surface containing the E' defect with the halogen particles. The reaction between the surface containing the E'defect and the F particle and the Cl particle was calculated and compared,respectively. At the same time, the adsorption of the same kind of particles on the surface containing NBOHC defects and E' defects was compared.