Dresden 2011 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 15: Linear and nonlinear Raman Spectroscopy

MO 15.3: Vortrag

Mittwoch, 16. März 2011, 15:15–15:30, MER 02

Raman and IR Spectroscopy of Carbonic Acid Isotopologues — •Christian Mitterdorfer¹, Juergen Bernard¹, Katrin Winkel^1,2, Marion Bauer², Frederik Klauser¹, Erwin Mayer², and Thomas Loerting¹ — ¹Institute of Physical Chemistry, A-6020 Innsbruck, Austria — ²Institut of General, Inorganic & Theoretical Chemistry, A-6020 Innsbruck, Austria

Owing to the ready decomposition in water and carbon dioxide, carbonic acid (H2CO3) seemed to be an instable molecule for a long time.[1] But in 1993 Mayer et al. synthesized a "stable" form of carbonic acid by protonation of bicarbonate and they characterized the solid through FTIR-spectroscopy.[2] Several studies pointed out carbonic acid's astrophysical relevance [3,4].

Here we present IR and Raman spectra of both crystalline polymorphs and their 13C and D isotopologues, which allow us to draw a conclusion concerning their structural symmetry. The rule of mutual exclusion indicates the presence of a center of inversion for the Beta-polymorph [5], but not for the Alpha-polymorph. Therefore the cyclic carbonic acid dimer is assumed as the building block (unit) for Beta-carbonic acid [5], whereas the Alpha-form is assumed to be built from monomeric carbonic acid.

[1]T. Loerting et al., ChemPhysChem 2010, 11, 2305-2309 [2]W. Hage et al., Journal of the American Chemical Society 1993, 115, 8427-8431 [3]M.H. Moore et al., Spectrochimica Acta Part A 2001, 843-858 [4]W. Hage et al., Science 1998, 279, 1332-1335 [5]I. Kohl et al., Angewandte Chemie International Edition 2009, 48, 2690-2694