Laboratory measurements of infrared absorption spectra of hydrogen-ordered ice; A Step to the exploration of ice XI in space

Arakawa, Masashi; Kagi, Hiroyuki; Fukazawa, Hiroshi

Astrophysical Journal; Supplement Series, 184(1), p.361 - 365, 2009/09

https://doi.org/10.1088/0067-0049/184/2/361

Infrared absorption spectra of ice were obtained at 4, 60, 100, 140, 160, and 240 K to make spectroscopic observations of hydrogen ordering at low temperatures. A broad peak observed at around 850 cm (11.7-181 m) was derived from libration of water molecules. The peak width was notably narrower at temperatures less than 140 K. A decrease in the peak width occurring in accordance with the formation of ice with ordered arrangements of hydrogen atoms was suggested from incoherent inelastic neutron-scattering studies. These results are consistent with ordering of hydrogen atoms. Existence of hydrogen-ordered ice in space is the subject of continuing astronomical debate. Our results demonstrate that the ordered ice in space is detectable using infrared telescopes and planetary exploration.