Published online by Cambridge University Press: 25 May 2016
Methods and accuracies of determining the lithium isotope ratio in stellar atmospheres from high resolution observations of the profile of the λ6708 Li i doublet are discussed, and recent results for metal-poor disk stars and halo stars are reviewed. The data are compared to models for the Galactic evolution of the 6Li abundance. It is concluded that a much larger data set is needed to understand properly the formation of 6Li in the interstellar medium as well as the depletion in stars.