  Understanding the nucleosynthesis and evolution of Asymptotic Giant Branch
(AGB) stars is of primary importance as they are the main producers of some of
the key elements in the Universe. They are the predominant sites for the slow
neutron-capture nucleosynthesis. The exact physical conditions and
nucleosynthetic processes occuring at the interior of AGB stars are not clearly
understood, that hinders a better understanding of the contribution of these
stars to the Galactic chemical enrichment. The extrinsic stars, which are known
to have received products of AGB phase of evolution via binary mass transfer
mechanisms, form vital tools to trace the AGB nucleosynthesis. The [Rb/Zr]
ratio is an important diagnostic to understand the average neutron density at
the s-process site and provide important clues to the mass of the companion AGB
stars. In this work we have presented the estimate of [Rb/Zr] ratios, based on
the high resolution spectroscopic analysis for a sample of Ba stars, and
discussed how it can be used to understand the characteristics of the AGB star.
Results from an analysis based on parametric model to confirm the mass of the
companion AGB star are also presented.
