Understanding the concept of randomness in inelastic electron tunneling excitations

Inelastic electron tunneling excitation has been realized in the last decade as an effective way to probe reliably detailed atomic structures and control precisely behaviors of surface adsorbates at a single molecule level. A good understanding of rich and complex processes on the surface under inelastic electron excitations is of great importance, not only from a fundamental scientific point of view but also for potential practical applications. In this perspective paper, we give an overview of recent developments on excitations and characterizations of inelastic electron tunneling processes in surface adsorbates and molecular junctions. Special attention has been paid to the understanding of the randomness of the processes. A recently proposed general statistical model is introduced which has resolved a long-standing puzzle concerning the experimentally observed non-integer power law relationship between the rate of molecular conformation changes and the tunneling current. The success of the new model is highlighted by its applications for molecular switches.