Structures Of Hydrated Alkali Metal Cations, M+(h2o)nar (m = Li, Na, K, Rb And Cs, N = 3-5), Using Infrared Photodissociation Spectroscopy And Thermodynamic Analysis

Ke, Haochen

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https://hdl.handle.net/2142/50844 Copy

Description

Title

Structures Of Hydrated Alkali Metal Cations, M+(h2o)nar (m = Li, Na, K, Rb And Cs, N = 3-5), Using Infrared Photodissociation Spectroscopy And Thermodynamic Analysis

Author(s)

Ke, Haochen

Contributor(s)

• Lisy, James M.
• van der Linde, Christian

Issue Date

2014-06-19

Keyword(s)

Mini-symposium: Beyond the Mass-to-Charge Ratio: Spectroscopic Probes of the Structures of Ions

Abstract

Alkali metal cations play vital roles in chemical and biochemical systems. Lithium is widely used in psychiatric treatment of manic states and bipolar disorder; Sodium and potassium are essential elements, having major biological roles as electrolytes, balancing osmotic pressure on body cells and assisting the electroneurographic signal transmission; Rubidium has seen increasing usage as a supplementation for manic depression and depression treatment; Cesium doped compounds are used as essential catalysts in chemical production and organic synthesis. Since hydrated alkali metal cations are ubiquitous and the basic form of the alkali metal cations in chemical and biochemical systems, their structural and thermodynamic properties serve as the foundation for modeling more complex chemical and biochemical processes, such as ion transport and ion size-selectivity of ionophores and protein channels. By combining mass spectrometry and infrared photodissociation spectroscopy, we have characterized the structures and thermodynamic properties of the hydrated alkali metal cations, i.e. M$^{+}$(H$_{2}$O)$_{n}$Ar, (M = Li, Na, K, Rb and Cs, n = 3-5). Ab initio calculations and RRKM-EE (evaporative ensemble) calculations were used to assist in the spectral assignments and thermodynamic analysis. Results showed that the structures of hydrated alkali metal cations were determined predominantly by the competition between non-covalent interactions, i.e. the water---water hydrogen bonding interactions and the water---cation electrostatic interactions. This balance, however, is very delicate and small changes, i.e. different cations, different levels of hydration and different effective temperatures clearly impact the balance.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/50844

DOI

https://doi.org/10.15278/isms.2014.RG06

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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