The distribution of the ionization fraction in dense medium computed from line ratios of ¹³CO/HCO⁺, CN/N₂H⁺and C¹⁸O/HCO⁺(left part of the figure, purple shaded area). In the right part of this figure, we show results on f_e derived from W(C₂H)/W(HCN), W(C₂H)/W(HNC), W(C₂H)/W(CN) in translucent medium (orange shaded area). Black dashed violins show distributions of all pixels that have detection in the corresponding intensity ratio. Purple violins show pixels only from regions where CN/N₂H⁺is detected, whereas orange violins show the same for W(C₂H)/W(HNC). We also show the median for each of these categories as a horizontal line.