Used in density gradient centrifugation to separate biological molecules like DNA and viruses based on buoyant density. Commonly employed in molecular biology and biochemistry research for purifying plasmid DNA and viral particles. Also utilized in some medical applications, such as in radiation therapy and diagnostic imaging, due to its ability to carry radioactive isotopes. In electronics, it serves in specialized devices like photomultiplier tubes and scintillation counters because of its high density and transparency to gamma radiation. Additionally, it finds use in chemical synthesis as a source of caesium ions in catalytic reactions.