From top to bottom: examples of galaxies at different ‘quenching stages’. First column: continuum RGB images extracted from the CALIFA datacubes using u– (blue), g– (green), and r– (red) bands. In the title, the galaxy name is given. Second column: discrete W_Hα maps. Here, blue indicates the region dominated by star formation, yellow shows diffuse gas regions, and red displays quenched regions (see text for more details). The title shows the ‘quenching stage’ and the median W_Hα across the full map. In the first and second column images, white ellipses mark the locations of 1 and 2 R_e, the green circle indicates the extend and position of the APEX beam at 230 GHz (26.2″), from which the spectra on the rightmost column are obtained. Third column: position of the galaxy on the SFR-M_* diagram. The grey dots show the location of every galaxy in our sample. The SFMS fit (black line) is taken from Cano-Díaz et al. (2016). The title gives the global distance from the SFMS, ΔSFMS. Fourth column: APEX ¹²CO(2-1) spectra (green) in T_mb units. All spectra have been shifted to 0 km s⁻¹ considering the systemic velocity of the galaxy (V_sys). The dotted line represents the observation σ_RMS. In the title, the S/N of the observation is given, together with the molecular gas mass. The assembled database contains CO information for several galaxies across each quenching stage and having different distances from the SFMS.