Dynamics of nanoscale precursor film near a moving contact line of spreading drops.

The spreading of liquids on solids is a commonplace phenomenon, discernible in various instances of everyday life. Despite the apparent simplicity of spreading, the underlying mechanisms are still not fully understood on a microscopic level, particularly at the moving edge between liquid and solid known as the contact line region. Here we show the time-dependent evolution of nanoscale films on a clean solid surface near the moving contact line. Our work contributes to the body of experimental evidence required to assemble a comprehensive understanding of microstructures at the vicinity of the contact line, bridging the gap between computational methods and theory. Moreover, this research will provide insight into the fundamental behavior of fluid spreading and other surface phenomena.