Frontiers of Microscopic Photoelectron Spectroscopy －Landscape of Real Space and Momentum Space－

Recently, two-dimensional imaging methods have been widely implemented in the photoelectron spectroscopy apparatus. In this special issue, we highlight the recent progress in the wide range of topics from topological insulator, superconductor to organic material. The key concept here is the interrelation between the real space and the momentum space. It is well recognized that our knowledge of surface and interface has been largely embodied based on the observation using various types of microscopic methods : not to mention, optical microscope, electron microscope, probe microscope, and others. On the other hand, the minute investigation in the momentum space (“k-space”) provides us with the detailed information on the band structure of the material, which governs the fundamental properties such as conductivity, photon absorption/emission, and various electronic excitations. Thus, investigation of the “both world” would undoubtedly give us more fundamental understanding of the behavior of both “localized electron” and “itinerant electron”, and further ramifications. We hope you enjoy an unprecedented landscape of real space and momentum space herein.