New, low-energy excitations in Mo107 and Mo109

New ground-state level with spin-parity $1/{2}^{+}$ is established in $^{109}\mathrm{Mo}$, 69.8 keV below the previously reported $5/{2}^{+}$ ground state in this nucleus, based on precise spectroscopy measurements of $\ensuremath{\gamma}$ radiation following spontaneous fission of $^{248}\mathrm{Cm}$ performed using the Eurogam2 array of anti-Compton spectrometers. Analogous measurement of $\ensuremath{\gamma}$ radiation following spontaneous fission of $^{252}\mathrm{Cf}$, performed using the Gammasphere array, confirms the new $1/{2}^{+}$ ground state of $^{107}\mathrm{Mo}$, proposed recently and establishes the isomeric character of the $5/{2}^{+}$ first excited state in $^{107}\mathrm{Mo}$. Two $\ensuremath{\beta}$-decaying isomers are suggested in $^{111}\mathrm{Mo}$ nucleus based on regular energy systematics, supporting previous predictions. Low-energy excitations in Mo isotopes are interpreted and compared to calculations reported in the literature. The results suggest shape transition from prolate to oblate deformation at $N\ensuremath{\ge}67$.