Mechanochemistry of shock-induced nanobubble collapse near silica in water

We have performed million-atom reactive molecular dynamics simulations to study shock-induced bubble collapse near an amorphous silica surface. We observe the formation of water jet during the bubble collapse, which collides on to the silica surface causing a hemispherical pit. Fragment analysis reveals substantial ionization activities in water followed by rapid increase in H ₃O ⁺ population during the pit formation. We have identified a shock-induced H ₃O ⁺ ion formation mechanism, in which transient five-coordinated silicon atoms play a pivotal role.