<page_title> Isotopes of dubnium </page_title> <section_title> List of isotopes </section_title> <table> <cell> 268Db <col_header> nuclide symbol </col_header> <col_header> excitation energy </col_header> </cell> <cell> 30.8(5.0) h <col_header> half-life </col_header> </cell> </table>
The longest-lived known isotope is ²⁶⁸Db.