A series of linesin the spectrum of neutral Li atoms rise from combinations of 1s^2 2p^1 ^2P with 1s^2 nd^1 ^2D and occur at 610.36nm, 460.29nm and 413-23nm. the d orbital are hydrogenic. It is known that the ^2P terms lies at 670.78nm above the ground state. whcih is 1s^2 2s^1 ^2S. calculate the ionization energy ofthe ground state atom.