Surface physicochemical properties and decay of the low-lying isomer in the 229Th nucleus

The effect of the ²²⁹Th nucleus proximity to the CsI surface on the decay probability of its anomalously low lying isomeric level is studied. Results of experimental and theoretical studies show that the CsI surface does not produce chemical bonding with Th and does not noticeably change its valence shells. Hence, it is an optimal substrate for measuring the probability of the ²²⁹Th isomer state decay via internal electron conversion. The half-life of the ²²⁹Th^m isomer in the thorium atom is calculated for neutral chemical environment.