In a sample of hydrogen atom in ground state electrons make transition from ground state to a particular excited state where path length $\left(2\pi r\right)$ is five times the de-broglie’s wavelength. When electrons make back transition to the ground state producing all possible photons. If photon having 2^nd highest energy of this sample is exactly used to excite the electron in a particular excited state of $L{i}^{2+}$ ion then the final excited state of  $L{i}^{2+}$ ion is_______