Time-resolved Observation of Surface Chemical Reactions by Using a Soft X-ray Energy Dispersive Surfaces XAFS

摘要

A novel experimental technique, soft X-ray energy dispersive surface XAFS (X-ray absorption fine structure), has recently been developed, by combining a new soft X-ray beamline with a position sensitive electron energy analyzer. The new technique enables us to obtain a NEXAFS (near-edge X-ray absorption fine structure) spectrum in one shot, without scanning the X-ray photon energy. The accumulation time for one NEXAFS spectrum for submonolayer adsorbate is reduced to 10-30 s, while it takes typically several minutes in the case of conventional method. Therefore it becomes possible to trace chemical reactions occurring on metal and semiconductor surfaces, and the local structure and electronic state during the surface reaction can be investigated. Some examples for the time-resolved observation of surface chemical reaction are demonstrated, together with the principle of the energy dispersive surface XAFS measurement.