CO ice desorption during warmup at a rate of 1 K min^-1 for sample deposited at 7 K (thick solid trace) and sample deposited at 20 K and cooled down to 7 K before warming up (thick dotted trace). The desorptions of H₂ in the samples deposited at 7 K (thin solid trace) and 20 K (thin dotted trace) are also shown (adapted from Muñoz Caro et al. 2010). The ion current (A) is plotted in a logarithmic scale for a better appreciation of the curve profile and corresponds roughly to partial pressure in mbar.