Nonadiabatic near-field optical polishing and energy transfers in spherical quantum dots

In the first half of this chapter, a novel fabrication method called nanophotonic polishing is reviewed. This method is a probeless and maskless optical processing technique that employs a nonadiabatic photochemical reactionnonadiabatic photochemical reaction . Nanophotonics has already brought about innovation in fabrication methods, such as with photochemical vapor deposition [1] and photolithography [2]. Conventional photochemical vapor deposition is a way to deposit materials on a substrate using a photochemical reaction with ultraviolet light that predissociates metal-organic molecules by irradiating gaseous molecules or molecules adsorbed on the substrate. Consequently, the electrons in the molecules are excited to a higher energy level, following the Franck-Condon principle. This is an adiabatic process, which indicates that the Born-Oppenheimer approximation is valid. However, it has been discovered that an optical near field with much lower photon energy (i.e., visible light) can dissociate the molecule. This phenomenon has been explained using a theoretical model of the virtual exciton-polariton exchange between a metal-organic molecule and the fiber probe tip used to generate the optical near field. In other words, this exchange excites not only the electron, but also molecular vibrations. This is a nonadiabatic process, which does not follow the Franck-Condon principle, and so the Born-Oppenheimer approximation is no longer valid.