Young stellar objects spectra measured with the Short Wavelength Spectrometer onboard the Infrared Space Observatory, compared to various laboratory ice mixtures recorded spectra. The optical depth astrophysical spectra are obtained from a continuum baseline subtraction. A close up on the dangling bond region is plotted in the left part of each panel. These spectra are compared to laboratory spectra of pure H₂O and CO₂ ice, and a H₂O:CO₂ 12:1 mixture. The CO₂ and a H₂O:CO₂ laboratory spectra are normalised to the CO₂ column density observed in the mid-IR. The H₂O dangling bond spectrum was normalized with the relation discussed in the preceeding section, assuming a porosity of 0.2, and integrating the OH stretching mode. See text for details.