Sub-Barrier Coulomb Excitation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>110</mml:mn></mml:mmultiscripts></mml:math>and Its Implications for the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>100</mml:mn></mml:mmultiscripts></mml:math>Shell Closure

The first excited ${2}^{+}$ state of the unstable isotope $^{110}\mathrm{Sn}$ has been studied in safe Coulomb excitation at $2.82\text{ }\text{ }\mathrm{MeV}/u$ using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, $B(E2:{0}^{+}\ensuremath{\rightarrow}{2}^{+})=0.220\ifmmode\pm\else\textpm\fi{}0.022{e}^{2}{b}^{2}$, strengthens the observation of the evolution of the $B(E2)$ values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of $^{108}\mathrm{Sn}$. It implies that the trend of these reduced transition probabilities in the even-even Sn isotopes is not symmetric with respect to the midshell mass number $A=116$ as $^{100}\mathrm{Sn}$ is approached.