Universität zu Köln

Stefanski, Johannes ORCID: 0000-0001-9419-3293, Schmidt, Christian and Jahn, Sandro ORCID: 0000-0002-2137-8833 (2018). Aqueous sodium hydroxide (NaOH) solutions at high pressure and temperature: insights from in situ Raman spectroscopy and ab initio molecular dynamics simulations. Phys. Chem. Chem. Phys., 20 (33). S. 21629 - 21640. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 1463-9084

Full text not available from this repository.

Abstract

Hydrothermal diamond anvil cell experiments in combination with Raman spectroscopy and first principles molecular dynamics simulations were performed to investigate the structure and dynamics of aqueous NaOH solutions for temperatures up to 700 degrees C, pressures up to 850 MPa and two different solute concentrations. The significant changes observed in the O-H stretching region of the Raman spectra between ambient and supercritical conditions are explained by both dynamic effects and structural differences. Especially important are a Grotthuss-like proton transport process and the decreasing network connectivity of the water molecules with increasing temperature. The observed transfer of Raman intensity towards lower wavenumbers by the proton transfer affects a wide range of frequencies and must be considered in the interpretation of Raman spectra of highly basic solutions. We suggest a deconvolution of the spectra using a model with four Gaussian functions, which are assigned to the molecular H2O and OH- vibrations, and one asymmetric exponentially modified Gaussian (EMG) function, which is assigned to [HO(H2O)(n)](-) vibrations.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Stefanski, Johannes UNSPECIFIED orcid.org/0000-0001-9419-3293 UNSPECIFIED Schmidt, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Jahn, Sandro UNSPECIFIED orcid.org/0000-0002-2137-8833 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-173100
DOI:	10.1039/c8cp00376a
Journal or Publication Title:	Phys. Chem. Chem. Phys.
Volume:	20
Number:	33
Page Range:	S. 21629 - 21640
Date:	2018
Publisher:	ROYAL SOC CHEMISTRY
Place of Publication:	CAMBRIDGE
ISSN:	1463-9084
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WATER; MOBILITY; SPECIATION; MECHANISM; HYDRATION; SPECTRA; FLUIDS; ROCKS; IONS; MELT Multiple languages Chemistry, Physical; Physics, Atomic, Molecular & Chemical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17310