Other
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p43c1689h&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P43C-1689
Other
[6020] Planetary Sciences: Comets And Small Bodies / Ices
Scientific paper
In astronomical ices, both compact and porous morphologies can be expected depending on the particular ice history [1]. These different morphologies might be relevant for the interpretation of astronomical observations as demonstrated in recent works [2], where the characteristic ν4 band of NH4+ at 6.85 μm, used in tentative identifications of this ion in astronomical observations, was shown to broaden and virtually disappear, when embedded in compact ice samples. In this work we present a more detailed characterization of the compact ices used in ref. [2], which are produced in the laboratory through the sudden freezing of water droplets on a cold substrate, a procedure similar to that reported by Loerting et al. [3] for the generation of hyperquenched (HQ) glassy water. The present study is based on infrared (IR) vibrational spectroscopy measurements of the solids. The compactness, specific surface area (SSA), and crystallization kinetics of the HQ samples is compared to that of vapour deposited (VD) ices. SSA values are estimated from the isothermal adsorption of CH4 and CO2 at 40 and 90 K. The rates of crystallization are determined at several temperatures up to 150 K by monitoring the position and width of the OD stretching band of isolated HDO molecules in ice samples with a 4% HDO content (see ref. [4] for a previous application of the method). From these experiments we derive the conclusions that follow. The much higher porosity of the VD samples is immediately evidenced by the IR absorption peak of uncoordinated OH dangling bonds, which is practically absent in the HQ ices. The SSA values for the HQ ices are about one order of magnitude lower than those for VD ices, and likewise, the rates of crystallization, are also found to be lower in HQ than in VD ices. These results, and their likely astrophysical implications, will be discussed at the conference. This work has been funded by the Spanish Ministry of Science under Grants FIS2007-61686 and FIS2010-16455. RE acknowledges Sabbatical grant PR2010-0012 from the same Ministry, at Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada. YRL acknowledges also funding from the CSIC JAE-doc program and OG from the CSIC JAE-doc and MCINN RyC programs. [1] a) Kouchi, A., Yamamoto, 1195, Progr. Cryst. Growth Charact. 30, 83, b) Baragiola R. A. 2003, Planet. Space Sci., 51, 953, c) Raut, U. et al. 2008, ApJ, 687, 1070. [2] a) Maté, B. et al. 2009, ApJL, 703, L178. b) Gálvez, O. et al., 2010, ApJ, 724, 539 [3] Loerting, T. et al. 2011 PCCP, 13, 8783. [4] Hague, W. et al. 1994, J. Chem. Phys. 100, 2743.
Escribano R. M.
Gálvez O.
Herrero Víctor J.
Maté Belén
Moreno Miguel A.
No associations
LandOfFree
A comparison of specific surface area and crystallization kinetics in compact and porous amorphous solid water does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A comparison of specific surface area and crystallization kinetics in compact and porous amorphous solid water, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A comparison of specific surface area and crystallization kinetics in compact and porous amorphous solid water will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-872139