TPD spectra of experiments involving ammonium formate. Left panels: TPD spectra of (a) pure NH₃ and (c) pure HCOOH. Right panels: TPD spectra of mixed NH₃ and HCOOH (b) without and (d) with a substrate of water. The desorption component around 208 K traces the desorption of NH₄ ⁺HCOO⁻; the ratio of its fragments, similar to those of pure molecules, indicates the dissociation of the salt during the desorption process back into the components NH₃ and HCOOH.