Dependence of the decay rate of 7Be on chemical forms

The decay rate of 7Be depends on the electron density at the nucleus and therefore may vary with the chemical environments of the Be atom. Using a 100% efficiency high-purity germanium detector, the decay constants of 7Be in Be2+(OH2)4, Be(OH)2 and BeO have been measured at unprecedented high precision (of ±0.01%), resulting in T1/2 = 53.69 d, 53.42 d, and 54.23 d, respectively. The observed difference, by as much as 1.5%, clearly indicates that decay rates of nuclides undergoing electron capture decay are not necessarily constant as has always been assumed in geological, oceanographic, and environmental studies.