  Excitation modes in the range $2/5 \geq \nu \geq 1/3$ of the fractional
quantum Hall regime are observed by resonant inelastic light scattering.
Spectra of spin reversed excitations suggest a structure of lowest spin-split
Landau levels of composite fermions that is similar to that of electrons.
Spin-flip energies determined from spectra reveal significant composite fermion
interactions. The filling factor dependence of mode energies display an abrupt
change in the middle of the range when there is partial population of a
composite fermion level.
