Fused silica with atomic-level super-smooth surface manufactured by dual-size synergistic nano CeO2 and its highly efficient polishing mechanism

• A kind of dual-size synergistic nano CeO 2 (DSS) is synthesized simply and efficiently. • The surface roughness of fused silica after polishing by DSS is 0.055 nm. • Ce-O-Si bonds at the SiO 2 -CeO 2 interface are discovered. • Ce single atoms in polished fused silica are detected for the first time. Fused silica has played a crucial role as high quality transmission/reflection optical components in ultra-precision optical systems, such as high-power lasers, gravitational wave detection, laser gyroscope and ultraviolet lithography systems, which the surface frequency error is one of the main principal elements affecting the performance of fused silica component. For decades, the pursuit of atomic-level super-smooth surface of fused silica has never stopped. Herein, a kind of dual-size synergistic nano CeO 2 (DSS) was prepared, and the atomic-level super-smooth surface of fused silica with 0.055 nm roughness was achieved by chemical mechanical polishing through using DSS. Compared with the “a not-to-exceed line” of the National Ignition Facility, the surface of fused silica polished by DSS has a reduction of 26 times in the 0.4–8.33 mm −1 spatial frequency domain of the power spectral density curve. More importantly, DSS can efficaciously suppress surface frequency errors while enhancing polishing efficiency. Furthermore, the cause for mid-spatial frequency error on fused silica surface is investigated from a new perspective of the excessive chemical action in chemical mechanical polishing. What’s more, Ce-O-Si bonds at the SiO 2 -CeO 2 interface are characterized, and Ce single atoms in polished fused silica are detected for the first time.