Differences in the decay constant of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ in various states of chemical combination were measured using the differential-ionization-chamber technique. The results are: $\left\{\lambda \right(\mathrm{BeO})-\lambda {\left(\mathrm{Be}{\mathrm{F}}_2\right)}_{\mathrm{amorph}}=(1.130\mathrm{}\pm 0.058)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right(\mathrm{BeO})-\lambda ({\mathrm{Be}}_4\mathrm{O}{\left({\mathrm{CH}}_3\mathrm{COO}\right)}_6)=(-0.724\mathrm{}\pm 0.057)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right(\mathrm{BeO})-\lambda (\mathrm{Be}{\mathrm{Br}}_2)=(1.472\mathrm{}\pm 0.063)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right({\mathrm{Be}}_4\mathrm{O}{\left({\mathrm{CH}}_3\mathrm{COO}\right)}_6)-\lambda {\left(\mathrm{Be}{\mathrm{F}}_2\right)}_{\mathrm{amorph}}=(1.852\mathrm{}\pm 0.082)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right(\mathrm{BeO})-\lambda (\mathrm{Be}{\left({\mathrm{C}}_5{\mathrm{H}}_5\right)}_2)=(0.795\mathrm{}\pm 0.074)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right(\mathrm{BeO})-\lambda ({\mathrm{Be}}^{2+}{\left({\mathrm{OH}}_2\right)}_4)=(-0.374\mathrm{}\pm 0.077)\times {10}^{-3\mathrm{}}\lambda (\mathrm{Be}),\}\left\{\lambda \right(\mathrm{Be}{\left({\mathrm{C}}_5{\mathrm{H}}_5\right)}_2-\lambda \left({\mathrm{Be}}^{2+}{\left({\mathrm{OH}}_2\right)}_4\right)=(-1.169\mathrm{}\pm 0.106)\times {10}^{-3\mathrm{}}\lambda \left(\mathrm{Be}\right).\mathrm{}\}$ The decay constant of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ is proportional to the electron density at the nucleus. These results can therefore be used to establish a scale for the relative electron density at the Be nucleus in different chemical combinations.

• Received 24 November 1969

DOI:https://doi.org/10.1103/PhysRevC.2.1616