  One possibility for the creation of ultracold, high-phase-space-density
quantum gases of molecules in the rovibrational ground state relies on first
associating weakly-bound molecules from quantum-degenerate atomic gases on a
Feshbach resonance and then transfering the molecules via several steps of
coherent two-photon stimulated Raman adiabatic passage (STIRAP) into the
rovibronic ground state. Here, in ultracold samples of Cs_2 Feshbach molecules
produced out of ultracold samples of Cs atoms, we observe several optical
transitions to deeply bound rovibrational levels of the excited 0_u^+ molecular
potentials with high resolution. At least one of these transitions, although
rather weak, allows efficient STIRAP transfer into the deeply bound vibrational
level |v=73> of the singlet X ^1Sigma_g^+ ground state potential, as recently
demonstrated. From this level, the rovibrational ground state level |v=0, J=0>
can be reached with one more transfer step. In total, our results show that
coherent ground state transfer for Cs_2 is possible using a maximum of two
successive two-photon processes or one single four-photon STIRAP process.
