  Time-resolved optical measurements of electron spin dynamics in modulation
doped InGaAs quantum wells are used to explore electron spin coherence times
and spin precession frequencies in a regime where an out of plane magnetic
field quantizes the states of a two-dimensional electron gas into Landau
levels. Oscillatory features in the transverse spin coherence time and
effective g-factor as a function of applied magnetic field exhibit a
correspondence with Shubnikov-de Haas oscillations, illustrating a coupling
between spin and orbital eigenstates. We present a theoretical model in which
inhomogeneous dephasing due to the population of different Landau levels limits
the spin coherence time and captures the essential experimental results.
