Relation between Interaction Distance and Coulomb Barrier Height

From the experimental data for lithium isotopes, we extracted the reduced interaction distance (\(d_{\text{I}}\)), the interaction radius (\(R_{\text{B}}\)), and Coulomb barrier height (\(V_{\text{B}}\)). Consequently, we found that the values of the reduced interaction distance are directly proportional to those of the reduced interaction radius, \(r_{\text{B}}\). The Coulomb barrier height for a \(\text{$^{8}$Li}+ \text{$^{208}$Pb}\) system is reduced by comparing with that of a \(\text{$^{7}$Li}+ \text{$^{208}$Pb}\) system, and this reduction is deduced to be caused by the valence neutron, which plays a role in the lowering of the barrier height.