We investigated the near resonant scattering and collision induced fluorescence of sodium atoms with doublet excited states in a weak laser field. By changing the frequency of the incident light and measuring the integral intensities of the components of the scattered light, the near resonant excitation cross-section of each sublevel was obtained as functions of the frequency detuning. Their variations are qualitatively explained by the interaction potential between the sodium atom and various collisional perturbing species. We have measured the variation of the induced D1 and D2 fluorescence with laser power, density of sodium atoms and pressure of buffer gas. It is shown that the relation is linear. The experimental results are in agreement with the theory.