Tracing the s-process: spectroscopic insights into chemical abundances in O- and C-rich evolved stars

Abstract Oxygen and carbon-rich AGB stars – and objects directly polluted by them – are excellent laboratories to investigate the nucleosynthesis and mixing processes occurring during the later phases of low- and intermediate-mass star evolution. The determination of the abundances of several s-elements is a key tool for constraining theoretical AGB models. This contribution discusses the main results, recent advances, and current problems on this subject.