Translational energy spectroscopy (TES) has been used to measure the relative populations of several of the long-lived excited states of six atomic (C+, N+, O+, Cl+, F+ and B+) ion beams formed by electron impact ionization using 70 eV electrons. The method used is based on the excitation/de-excitation method originally devised by Moore and is discussed in detail with particular reference to the choice of O2 and NO as collision gases on spin-conservation grounds. The relative metastable populations of C+, N+, O+ and B+ reported in this paper are similar to other reports found in the literature. However, there are known reports of any measurements of the fractional abundances of the metastable states in Cl+ and F+ ion beams formed from BCl3 and CHF3 precursors respectively.