The g-factors of microsecond isomers in neutron-rich nuclei produced in fission reactions were investigated at the FRagment Separator (FRS) at GSI and at the Lohengrin mass separator at the ILL reactor, Grenoble. The mass separators were used in both cases to select and identify unambiguously the recoiling fission fragments. The time-dependent perturbed angular distribution (TDPAD) method was applied in combination with the ion-gamma correlation technique to measure the g-factors of isomeric levels in 126Sn (I=7-, T1/2=5.9(8)us) and 127Sn (I=19/2+, T1/2=4.5(3)us) produced in relativistic fission at GSI and 98Y (I=4-, T1/2=8.0(2)us) and 136Xe (I=6+, T1/2=2.95(9)us) produced in a thermal-neutron-induced fission reaction at ILL. In all four investigated nuclei the half-lives determined for the isomeric levels of interest from the present data sets were found to be in good agreement with the values reported in literature. However, in order to apply the TDPAD technique to extract the g-factors of isomeric states, spin-alignment is very important. Unfortunately, no spin-alignment was observed for the states of interest in 98Y (I=4-) and 136Xe (I=6+) produced in a thermal-neutron-induced fission at ILL. This can be explained by the fact that in such a reaction the spin-alignment produced initially was lost during the transportation and separation process through the recoil mass separator. Thus, a determination of the g-factors for the isomeric levels of interest was not possible in this case. The measurement performed at GSI constitutes the first experimental observation of spin-alignment in a relativistic fission reaction. This allowed the measurement of the g-factors for the isomeric 7- and 19/2+ states in the neutron-rich nuclei 126Sn and 127Sn, respectively. A good agreement was obtained between the experimental values, g_exp(7-;126Sn)=-0.097(3) and |g_exp|(19/2+;127Sn)=0.163(10), and those calculated in the framework of shell-model, confirming the proposed n (h^-1_11/2 d^-1_3/2)]7- and [(5-x nh^-1_11/2)]19/2+ quasiparticle configurations, respectively, for the two isomers investigated in the present work
