Observation of a Time-Dependent Recoilless Fraction

Abstract

We have directly observed a time-dependent recoilless fraction. This effect is seen using delayed-coincidence Mössbauer spectroscopy. The time-dependent recoilless fraction is observed at the ${\mathrm{Fe}}^{3+}$ site and not at the ${\mathrm{Fe}}^{2+}$ site in a CoS${\mathrm{O}}_4$·7${\mathrm{H}}_2$O source. The relaxation time of the recoilless fraction is estimated to be between 10 and 100 nsec. Delayed-coincidence Mössbauer spectroscopy measurements on sources of Co${\mathrm{Cl}}_2$·6${\mathrm{H}}_2$O and Co${\left(\mathrm{N}{\mathrm{H}}_4\right)}_2$ ${\left(\mathrm{S}{\mathrm{O}}_4\right)}_2$·6${\mathrm{H}}_2$O did not show such an effect.