Predicted abundances (solid lines) of the CS (top row), H₂S (middle row), and SO (bottom row) by models with different chemical desorption schemes, together with the observed abundances in TMC 1, at times 0.1−1−10 Myrs. Noticethat there is an extinction interval in which the observed H₂S fit to different chemical desorption schemes. This can be interpreted as a change in the grain surface composition. The vertical dashed line corresponds to A_v = 6 mag. The interval 2.5−8 mag around this value is shaded in all subplots.