  Stimulated Raman Adiabatic Passage (STIRAP) is a widely used method for
adiabatic population transfer in a multilevel system. In this work, we study
STIRAP under novel conditions and focus on the fractional, F-STIRAP, which is
known to create a superposition state with the maximum coherence. In both
configurations, STIRAP and F-STIRAP, we implement pulse chirping aiming at a
higher contrast, a broader range of parameters for adiabaticity, and enhanced
spectral selectivity. Such goals target improvement of quantum imaging, sensing
and metrology, and broaden the range of applications of quantum control
techniques and protocols. In conventional STIRAP and F-STIRAP, two-photon
resonance is required conceptually to satisfy the adiabaticity condition for
dynamics within the dark state. Here, we account for a non-zero two-photon
detuning and present control schemes to achieve the adiabatic conditions in
STIRAP and F-STIRAP through a skillful compensation of the two-photon detuning
by pulse chirping. We show that the chirped configuration - C-STIRAP - permits
adiabatic passage to a predetermined state among two nearly degenerate final
states, when conventional STIRAP fails to resolve them. We demonstrate such a
selectivity within a broad range of parameters of the two-photon detuning and
the chirp rate. In the C-F-STIRAP, chirping of the pump and the Stokes pulses
with different time delays permits a complete compensation of the two-photon
detuning and results in a selective maximum coherence of the initial and the
target state with higher spectral resolution than in the conventional F-STIRAP.
