Figure 1: Experimental electric beam profiles of CoSn₁₀ (left) and CoSn₁₁ (right) at 16K nozzle temperature and 24kV deflection voltage. The quantum chemical structures are found by global optimization and the electric beam profile is simulated by using the dipole moment and the moments of inertia of the structure to solve the Euler equations in an electric field (black line). The structure motive of CoSn₁₀ is also present in CoSn₁₁ in which the extra tin atom just sits at the side of the Sn₁₀ cage, leading to a great increase in the dipole moment of the cluster.