Extended Data Fig. 4: The observed spectra compared to laboratory data for pure and mixed ices, normalised to the peak of the ~ 3 μm absorption band of H2O, with no local baseline correction.
From: Detection of the elusive dangling OH ice features at ~2.7 μm in Chamaeleon I with JWST NIRCam
Lower panel: observed optical depth spectrum (black) derived by stacking the spectra of the four highest flux sources (object 077 in green, object 282 in dark blue, object 268 in red, and object 092 in light blue). Upper panel: Water ices deposited onto substrates held at increasing temperatures to form increasingly compact amorphous ices; ices prepared at 10 K (light blue), 60 K (pink), 90 K (orange) and normalised to 3.05 μm. Measured in transmission at 10 K. Second panel from top: water ices prepared by increasingly energetic processes to form increasingly compact amorphous ices (background deposition at 10 K (dark blue), background deposition at 110 K (orange), formed on surface by radical reactions at 10 K (green)), normalised to 2.95 μm and measured by RAIRS at 10 K. Third panel from top: laboratory binary ice mixtures of H2O with CO2 (dark blue), CO (orange), NH3 (light blue), CH4 (green), and an example ‘disruptive’ organic molecule (in this case pyrene, yellow dash-dot) measured in transmission. A pure H2O spectrum deposited at 60 K is shown in pink. Laboratory spectra were selected such that the abundance of the second molecular species in the H2O ice was similar to that determined for NIR38 (object 077) in refs. 8,25.
