Photodestruction cross sections of ethanol in pure and mixed ice samples (1 Mb = 10⁻¹⁸ cm²). (a) Results are plotted versus the mixing ratio with CO. The black data markers correspond to Series 1, wherein the initial column density of ethanol is fixed at around 2 × 10¹⁶ cm⁻², and the mixing ratio and total initial thickness vary. The blue line shows the fit summarized in Eq. (31). (b) Results are plotted for data series where the fractional composition of the initial ice mixture is held constant and the total thickness is varied.