The effective radiative rates for Rb (5P3/2) resonance level in the presence of Ar or N2 have been determined. Rb atoms were excited to the 5P3/2 state using a single-mode diode laser(pumping laser). The single-mode laser beam (probing laser) tuned to the 5P3/2→7S1/2 transition passes through samples paralled to the pumping laser. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counter propagating single-mode diode laser beam (probing laser). In the presence of radiation trapping, the effective radiative rate is the product of spontaneous radiation rate and transmission factor, which describes the average probability that photons emitted within the fluorescence detection region can pass through the optically thick vapor without being absorbed. The transmission factor is calculated by combining the 5P3/2 atom density and its spatial distribution and collisional broadening of 5P3/2←5S1/2 transition line. The effective radiative rates of the Rb D2 line as a function of the Ar or N2 pressure P are obtained. The fluorescence intensity I780 of the 5P3/2→5S1/2 emission is measured simultaneously. For 5P3/2-Ar system the measured fluorescence ratios determine the ratios of the effective radiative rates at different Ar densities. These ratios are in agreement with theoretical evaluation. For 5P3/2-N2 system the electronic to vibrational energy transfer has been investigated. The cross section was obtained.