Water ice formed by vapor deposition and liquid aerosol injection: A comparison study using reflectance absorption infrared spectroscopy

Low temperature water ices (90-165 K) were produced via flash freezing during liquid aerosol injection (LAI) or vapor deposition (VD). The infrared spectral shapes of the O-H stretch at 3 μm (3300 cm-1) and the H-O-H bend at 6 μm (1600 cm-1) indicate that the two deposition methods produce different ice structures, with VD producing predominately more ordered structures than LAI at every deposition temperature studied. These different amorphous structures behave similarly with heating but remain spectrally different until crystallization, consistent with previous findings that hyperquenched glassy water and amorphous solid water are structurally different. This work demonstrates the utility of studies with experimental systems capable of directly comparing ice formation methods. To determine the presence of crystalline ice, the shape of the 3-μm feature is most useful, while the intensity of the 6-μm feature is a reliable indicator of amorphous ice and liquid-like behavior of the ice with heating. Liquid-like phases can be produced through LAI at all temperatures studied and through VD at the glass transition temperature of 136 K.