Prompt γ-ray spectroscopy of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Mo</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>104</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Mo</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>108</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>fission fragments

The level structures of the neutron-rich $^{104}\mathrm{Mo}$ and $^{108}\mathrm{Mo}$ nuclei have been investigated by observing prompt \ensuremath{\gamma} rays emitted in the spontaneous fission of $^{248}\mathrm{Cm}$ with the EUROGAM spectrometer. Levels with spins up to 12\ensuremath{\Elzxh} have been observed and \ensuremath{\gamma} branching obtained. The data can be satisfactorily described when $^{104,108}\mathrm{Mo}$ are considered as axially symmetric nuclei: in $^{104}\mathrm{Mo}$, rotational bands based on the ground state, the one-phonon and the two-phonon \ensuremath{\gamma}-vibrational states and a quasiparticle state have been observed, whereas in $^{108}\mathrm{Mo}$ the information is limited to the yrast band and the one phonon \ensuremath{\gamma} band. \textcopyright{} 1996 The American Physical Society.