Carbamic acid: molecular structure and IR spectra

Infrared absorption spectra of mixed H ₂O, NH ₃ and ¹²CO ₂/ ¹³CO ₂ ices subjected to 1 MeV proton irradiation were investigated. The results of analyses of the spectra suggest formation of carbamic acid at low temperatures. The stability of this compound in the solid phase is attributed to intermolecular hydrogen bonding of the zwitter-ion (NH ₃⁺COO ^-) structure.