Schematic illustration of the measurement principle. First, the H₂O:CH₃OH:N₂ ice is irradiated at low temperatures T₁ at a current I₁ for a time t₁, which leads to the formation of a soluble organic matter analog. The sample is then heated above the water sublimation temperature to a temperature T₂ and irradiated at a current I₂ for a second time t₂, resulting in the formation of organic macromolecular matter from the soluble organic matter analog. The aluminum foil is not displayed in the schematic. The schematic is adapted in part from Danger et al. (2022).