Experimental determination of the energy level of Be(1s22s2p2)4P

Abstract
We report the first experimental measurements for the energy level of a metastable state of Be. The ions were produced in sequential charge-exchange collisions between 50- to 60-keV Be+ ions and lithium vapor. The center-of-mass energy of autodetaching electrons was found to be 2.53±0.09 eV. This result is in good agreement with previously calculated values for the Be(1s22s2p2 )4P state energy.