Estimates of the 1350 cm⁻¹ band area in a H₂O:CH₃OH:NH₃=1:1:1 mixture bombarded with 200 keV H⁺. Panel A: Integration of the optical depth after the subtraction of a linear continuum between about 1360 and 1330 cm⁻¹; Panel B: Multi-Gaussian fit between 1450–1250 cm⁻¹ and estimate of the 1350 cm⁻¹ band area from the integration of the optical depth of the synthetic Gaussian curve.