Nuclear resonance fluorescence in94Mo,95Mo and96Mo

Using gaseous sources of Tc₂O₇ containing the radioactive isotopes⁹⁴Tc,⁹⁵Tc and⁹⁶Tc, levels at 871.0keV (⁹⁴Mo), 765.8, 820.6, 947.8, 1074.0keV (⁹⁵Mo) and 778.3keV (⁹⁶Mo) have been excited. From the effective cross sections for nuclear resonance scattering and from the lifetimes of the 947.8, 1074.0 and 778.3keV levels known from Coulomb excitation experiments the profiles of theγ-lines have been determined. A broadening of theγ-lines due to Coulomb explosion of the molecules has been observed. Making use of the line profiles, lifetimes ofΤ=(6.4±1.0) ps andΤ=(0.90 ± 0.20) ps have been determined for the 765.8 and 820.6keV levels, respectively. The angular distribution of the resonantly scattered radiation yields an amplitude ratioδ for the mixed M1 E2 765.8keV transition ofδ=0.14 _?0.009 ^+0.08 . TheB(E2) from a Coulomb excitation experiment and the lifetimeΤ from the present experiment yield ¦δ¦=0.07±0.01 for the 820.6keV transition.