Model spectra and S/N maps for Al I, AlH, Ca II, and Cr I. Left panels: model spectra for each chemical species. Middle panels: corresponding S/N maps, combining data from both CARMENES and PEPSI instruments. The white dotted lines indicate the position of K_p – Δ v where the S/N reaches its maximum. Right panels: CCFs at the K_p values corresponding to the maximum S/N detections.