Units and Measurements: JEE Main 2019 Physics question

The force of interaction between two atoms is given by F = $\alpha$$\beta$exp $\left( { - {{{x^2}} \over {\alpha kt}}} \right)$; where x is the distance, k is the Boltzmann constant and T is temperature and $\alpha$ and $\beta$ are two constants. The dimension of $\beta$ is :