Internal conversion of nuclear transition in the ${}^{235m}U@C_{60-n}X_n$ molecules and related compounds

Abstract

The internal conversion of nuclear transition in the ${}^{235}U$ atom is considered. The low-energy $\gamma-$quanta ($E_{\gamma} \approx$ 76.8 $eV$) are emitted during the $E3-$transition from the excited state ($I = (\frac12)^+$) of the ${}^{235}U$ nucleus to its ground state ($I = (\frac72)^-$). The decay rate of this ${}^{235m}U$ isomer ($E \approx 76.8$ $eV$) noticeably depends upon the chemical composition and actual physical conditions (i.e. temperature $T$ and pressure $p$). By varying such a composition and physical conditions one can change the life-time of the ${}^{235m}U$ isomer to relatively large/small values. A specific attention is given to the fullerene molecules containing the central ${}^{235}U$ atom. It is shown that the decay rate $\lambda$ of the ${}^{235m}U$ isomer in the ${}^{235m}U@C_{60-n}X_n$ molecules and related compounds can differ significantly from the values obtained for isolated ${}^{235}U$ atoms. Some applications of this effect are considered.