  We report a combined experimental and theoretical simulation of multiply
scattered light dynamics in an ultracold gas of 85Rb atoms. Measurements of the
spectral dependence of the time-decay of the scattered light intensity,
following pulsed excitation with near resonance radiation, reveals that the
decay for long times is nearly exponential, with a decay constant that is
largely independent of detuning from resonance. Monte Carlo simulations of the
multiple scattering process show that, for large detunings, near resonance
scattering of Fourier components of the excitation pulse plays a significant
role in the effect. This interpretation is supported by the observations, and
successful modelling, of beating between Rayleigh scattered light at the
excitation carrier frequency with the Fourier components of the excitation
pulse that overlap significantly with the atomic resonance.
