Ices of CO2/H2O Mixtures. Reflection-Absorption IR Spectroscopy and Theoretical Calculations

Mate, B. and Galvez, O. and Martin-Llorente, B. and Moreno, M. A. and Herrero, V. J. and Escribano, R. and Artacho, E. (2008) Ices of CO2/H2O Mixtures. Reflection-Absorption IR Spectroscopy and Theoretical Calculations. Journal of Physical Chemistry A, 112 (3). pp. 457-465. DOI 10.1021/jp0769983

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Abstract

Ice mixtures of CO2 and H2O are studied using Fourier transform reflection-absorption infrared (RAIR) spectroscopy. Mixtures are prepared by sequential deposition or co-deposition of the two components from the gas phase onto an Al plate kept at 87 K inside a low-pressure chamber. Two CO2 structures are found in most experiments: a crystalline form similar to pure CO2, which evaporates when warming at 105 K, and a noncrystalline species which remains embedded in amorphous water ice after warming. Significant spectral variations are found depending on the deposition method and the thickness of the solid. Features characteristic of the RAIR technique appear in the spectral regions of the normal modes of the bending and asymmetric stretching CO2 vibrations. Simulations using Fresnel theory and Mie scattering are carried out with acceptable agreement with the experimental spectra of solids of variable thickness, from 1 ím to the limit of nanoparticles. Theoretical calculations of a pure CO2 crystal are performed. The relaxed geometry of the solid and its vibrational spectrum are determined and compared to the experimental results.

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA55 2008 P
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Journal of Physical Chemistry A
Volume: 112
Page Range: pp. 457-465
Identification Number: 10.1021/jp0769983
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:03
Last Modified: 23 Jul 2013 10:07
URI: http://eprints.esc.cam.ac.uk/id/eprint/518

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