The X-band excited-state electron paramagnetic resonance (EPR) spectra of M
n-12-acetate nanomagnet crystals has been measured. Three lines belonging t
o the m = -1 <-> 0 transition at H-C = 600 G and to the m = 0 <-> -1 and m
= -2 <-> -1 high-field transitions at 7800 and 9200 G, respectively, were d
etected below 50 K in agreement with the energy level scheme obtained from
high-field EPR. The lines are rather broad. T-2 is shorter than 30 ns and T
1T2< 10(-15) s(2). Similarly broad excited-state EPR spectra were also obse
rved in a Fe(8) single crystal.