Electron-Capture Decay Rate of ⁷Be Encapsulated in C₆₀ Cages

Abstract

The decay rate of ⁷Be electron capture (EC) was measured in C₆₀ and Be metal with a reference method. The halflives of ⁷Be endohedral C₆₀ (⁷Be@C₆₀) and ⁷Be in Be metal (Be metal (⁷Be) ) were found to be 52.65±0.04 and 53.25±0.04 days, respectively. This amounts to a 1.13% difference in the EC-decay half-life between ⁷Be@C₆₀ and Be meta (⁷Be). The result is a reflection of the different electron wave-functions for ⁷Be inside C₆₀ compared to when ⁷Be is in a Be metal. Here, the magnitude of the average charge-transfer from the L (2s) electrons of the ⁷Be atom plays an important role in such variation in the decay constant in the environments.