[en] Fractions of long-lived excited species in noble-gas ion beams, produced by various methods, have been determined using slow ion impact induced electron emission from clean polycrystalline tungsten. Investigations with ion beams produced by single electron impact on atoms permitted the determination of cross sections for the production of singly charged metastable ions of the noble gases Ar, Kr and Xe. The cross sections obtained increase steeply from threshold up their maximum values of about 10^-17 cm² within 1.5 times threshold energy. Processes responsible for production of these metastable ions are discussed and the method applied is compared with other techniques for metastable ion detection. (author)