The adsorption and desorption of CO on and from amorphous H2O ice at astrophysically relevant temperatures has been studied using temperature programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). Solid CO is able to diffuse into the porous structure of H2O at temperatures as low as 15 K. When heated, a phase transition between two forms of amorphous H2O ice occurs over the 30-70 K temperature range, causing the partial collapse of pores and the entrapment of CO. Trapped CO is released during crystallization and desorption of the H2O film. This behavior may have a significant impact on both gas-phase and solid-phase chemistry in a variety of interstellar environments.
|Number of pages||5|
|Publication status||Published - 1 Feb 2003|