Core electron excitation possesses an attractive potential of inducing selective chemical bond breaking. Compared to valence excitation, core excitation takes place within a small area because of its spatial localization and atomic selectivity. Therefore, a specific atom in a molecule can be excited selectively. The core-excited state is quite unstable with an extremely high energy, so consecutive decay processes—Auger decay and ionic dissociation—can occur in the vicinity of the excited atom. From this concept, site-selective ionic fragmentation has been widely and successfully investigated in various core-excited molecular systems. This paper briefly describes the characteristics of core excitation and experimental methods, and then reviews representative recent studies about site-selective chemical bond breaking induced by core excitation.
