0 50000 1e+05 1.5e+05 t 0 0.2 0.4 0.6 0.8 1 population FIG. 2: Population transfer in the three-level λ -system, achieved via the resonant Raman tran- sitions and using an optical frequency comb as in Eq.(1) having the carrier frequency and the modulation frequency in resonance with one-photon transitions in the λ -system. The values of the parameters are the carrier frequency ω$_{L}$ =5.9, (410.7 THz), the modulation frequency Ω=4.9, (340.7 THz), the modulation amplitude Φ 0 = 4, and the peak Rabi frequency Ω$_{R}$=1, (70THz); the system one-photon transition frequencies are ω 21 = Ω, ω 32 = ω$_{L}$ . Stepwise, adiabatic accumulation of the population is observed in state | 3 > , (green), which is the ultracold KRb state. The population of the Feshbach state | 1 > , (black), reduces gradually to zero, while the excited state manifold | 2 > , (red), is slightly populated during the transitional time. Full population transfer is accomplished in 112 pulses. within 42 pulses and accomplished in about 1 ns. However, the population of the transitional, electronic excited state is substantial, almost 50%. Compared to the resonance case, the population dynamics is faster with less number of pulses in the pulse train involved into full population transfer. Notably, there is a strong dependence of the efficiency of population transfer on the value of the amplitude Φ 0 of sinusoidal modulation of the phase across individual pulse in the pulse train. For the resonant excitation, population dynamics was calculated using different values of the parameter Φ 0 , the results are presented in Fig.4 for Φ 0 = 3 , 5 , 8. The desired adiabatic accumulation of the population in the final state is not achieved for any of these values of Φ 0 . To understand the impact of the modulation amplitude Φ 0 , we analyzed the 6