title: The local atomic structures of liquid CO at 3.6 GPa and polymerized CO at 0 to 30 GPa from high-pressure pair distribution function analysis.
abstract: The local atomic structures of liquid and polymerized CO and its decomposition products were analyzed at pressures up to 30 GPa in diamond anvil cells by X-ray diffraction, pair distribution function (PDF) analysis, single-crystal diffraction, and Raman spectroscopy. The structural models were obtained by density functional calculations. Analysis of the PDF of a liquid CO-rich phase revealed that the local structure has a pronounced short-range order. The PDFs of polymerized amorphous CO at several pressures revealed the compression of the molecular structure; covalent bond lengths did not change significantly with pressure. Experimental PDFs could be reproduced with simulations from DFT-optimized structural models. Likely structural features of polymerized CO are thus 4- to 6-membered rings (lactones, cyclic ethers, and rings decorated with carbonyl groups) and long bent chains with carbonyl groups and bridging atoms. Laser heating polymerized CO at pressures of 7 to 9 GPa and 20 GPa resulted in the formation of CO(2).
authors: Institut für Geowissenschaften, Goethe-Universität Frankfurt, 60438 Frankfurt am Main (Germany), Fax: (+49) 69-798-40109. Rademacher@kristall.uni-frankfurt.de.
authors: Nadine
authors: N
authors: Rademacher
authors: Lkhamsuren
authors: L
authors: Bayarjargal
authors: Wolfgang
authors: W
authors: Morgenroth
authors: Björn
authors: B
authors: Winkler
authors: Jennifer
authors: J
authors: Ciezak-Jenkins
authors: Iskander G
authors: IG
authors: Batyrev
authors: Victor
authors: V
authors: Milman
keywords: carbon monoxide; high-pressure reactions; liquids; pair distribution functions; polymerization