Carbon and nitrogen abundances as indicators of material mixing in evolved stars

Carbon and nitrogen abundances are among most useful quantitative indicators of mixing processes in evolved stars. Because of the first dredge-up abundances of 12C decrease while abundances of 13C and 14N increase. These alterations become efficient again on the red giant branch when stars reach the so-called luminosity bump, and depend on stellar evolutionary stage, mass, metallicity, rotation, magnetic activity and other parameters and processes. An overview is provided on observational analyses of evolved low mass giants accomplished using the Nordic Optical Telescope.