First observation made of quantum-tunneling diffusion of hydrogen atoms on ice

(Phys.org)--As long as the temperature is above absolute zero, gas molecules are always in constant random motion. They may diffuse--or spread out--through three-dimensional space or, in a process called "surface diffusion," along the two-dimensional surface of a solid. The most well-known mechanism to explain surface diffusion is a classical mechanism called thermal hopping, in which gas molecules jump from one adsorption site (the place where the gas molecules attach to the surface) to another...