  Optical orientation experiments have been performed in GaAs epilayers with
photoexcitation energies in the 3 eV region yielding the photogeneration of
spin-polarized electrons in the satellite L valley. We demonstrate that a
significant fraction of the electron spin memory can be conserved when the
electron is scattered from the L to the $\Gamma$ valley following an energy
relaxation of several hundreds of meV. Combining these high energy
photo-excitation experiments with time-resolved photoluminescence spectroscopy
of $\Gamma$ valley spin-polarized photogenerated electrons allows us to deduce
a typical L valley electron spin relaxation time of 200 fs, in agreement with
theoretical calculations.
