Experimental TPD curves for ﹩{{\mathrm{NH}}_{4}}^{+}﹩NH2COO− obtained (a) from the mass spectra by taking the signal at mass 61 and (b) from the IR spectra by taking the first temperature derivative of the integrated intensity of the 1550 cm−1 band. The curves were measured with a ramp rate of 2 K minute−1 for 200 nm ice on carbon grains after 4 hr of the isothermal kinetic experiment.