The second metastable state of Kr, 5s’[1/2](0), was generated from the first metastable state, 5s[3/2](2), by optical pumping in a flow reactor. Under optimum conditions, the entire Kr(5s[3/2](2)) concentration could be removed with more than 40% conversion to the Kr(5s’[1/2](0)) state, which is stable in He carrier gas. The Kr(5s’[1/2](0)) and Kr(5s[3/2](2)) states have the Kr+(P-2(1/2)) and Kr+(P-2(3/2) ion cores, respectively, as do the Kr(+)X(-)(D) and Kr(+)X(-)(B,C) states. The reactions of a series of fluorine-, chlorine-, and bromine-containing molecules, RX, with the Kr(5s’[1/2](0)) and Kr(5s[3/2](2)) atoms were studied by measuring the total quenching rate constants and by observing the KrX(B,C,D) product emission spectra. In contrast to the Kr(5s[3/2](2)) atoms, which give KrX(B and C) products, the Kr(5s’[1/2](0)) atoms have a high propensity to give KrX(D) plus a lesser amount of KrX(B), depending on the reagent, as products. Discrimination against KrX(C) formation by reactions of Kr(5s’[1/2](0)) atoms is severe. The reactions with F-2, NF3, and N2F4 exhibit the highest conservation of the Kr+(P-2(1/2)) core, and these Kr(5s’[1/3](0)) reactions give >70% KrF(D). The total quenching constants of Kr(5s’[1/2](0)) atoms generally are equal to those for Kr(5s[3/2](2)), but the branching fractions for KrX* formation from Kr(5s’[1/2](0)) atoms generally are smaller than for Kr(5s[3/2](2)) atoms. A correlation diagram based on conservation of Kr+ ion-core state and Omega=0(-) is developed to discuss these trends and the reactions of the Xe/6s’[1/2](0) and 6s[3/2](2)) atoms. Due to the absence of KrX(C-A) emission from the Kr(5s’[1/2](0)) atom reactions, the KrX(B-A) and Kr(D-A) transitions could be observed and the radiative branching ratios to the X and A states were assigned.