Low- and intermediate-mass stars (M < 8M☉) eject a substantial amount of their material (up to 80%) into space during a late phase of stellar evolution, the asymptotic giant branch (AGB) phase.
Consequently, AGB stars are major players in the cosmic gas and dust cycle. An extended circumstellar envelope (CSE) will be created around the star as a consequence of the intense mass loss. Observations of molecular species and dust content in CSEs help us to broaden our knowledge on mass-loss processes, stellar properties, and the CSE chemistry. In this presentation, I will give an introduction to the CSE chemistry with a focus on the UV chemistry. Then, I will show how high spectral and spatial resolution ALMA observations can help us to quantify the impact of various sources of UV radiation in the CSE chemistry around evolved stars.
