Level energy(keV) Spin & Parity ---------------------------------------- ground state 0+Mass (The Ame2012 atomic mass evaluation (II) by M.Wang, G.Audi, A.H.Wapstra, F.G.Kondev, M.MacCormick, X.Xu, and B.Pfeiffer Chinese Physics C36 p. 1603-2014, December 2012)
218.023523472 ± 0.000019568 (amu) [mass excess = 21911.973 ± 18.228 (keV) ]Evaluated Data Libraries
Links to the libraries.