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The laboratory of radiochemistry aims at a comprehensive understanding of structure and reaction of exotic atoms and molecules. The exotic atoms and molecules are the analog of normal atoms and molecules in which one or more of the electrons or nuclei are replaced by other charged particles, such as a positron, a muon, an antiproton, and a stau. These particles shed a light on new properties of chemical compounds. Some of them are used as a probe to investigate the microscopic nature of materials. Others drastically change the structure of the chemical compounds, and another interaction such as nuclear reaction takes place. Therefore, the subject of the exotic atoms and molecules is in the interdisciplinary region. It partially covers material science, fundamental physics and cosmology, as well as radiochemistry. In this laboratory, exotic atom and molecule are studied both theoretically and experimentally.