Low-lying states in La-128(57) and Ba-128(56) have been investigated b
y gamma-ray spectroscopy after the beta decays of Ce-128(58) and La-12
8(57). For the EC+beta(+) decay of Ce-128, a new halflife has been det
ermined to be 4.1 +/- 0.3 min. In La-128 a new beta-unstable isomeric
state with a halflife shorter than 2 min is suggested in addition to a
previously known isomeric state with the halflife of 5.2 min. A tenta
tive level scheme of La-128 at low excitation energies has been constr
ucted from the gamma-gamma coincidence measurement after the beta deca
y of Ce-128. The gamma-gamma angular correlation for gamma rays from B
a-128 after the beta decay of La-128 suggests that the spin-parity ass
ignment of I-pi = 4(-) or 5(+) is preferable for the 2424.9 keV level
which is populated via the beta decay of the 5.2-min isomeric state wi
th a logft value of 5.6. For the 2877.1 keV level observed with logft
= 5.8, a preferable spin-parity assignment is 5(-) or 6(+). On the bas
is of these decay properties and low-lying excited states in neighbori
ng odd mass nuclei, the spins and parities of isomeric states in La-12
8 are proposed to be (1(+) or 2(+)) for the low-spin state, while (5(/-) or 6(+)) for the high-spin state, within the limit of zero order a
pproximation to the proton-neutron couplings.