Rapid Water-Ion Dynamics Revealed | May 24, 2010 Issue - Vol. 88 Issue 21 | Chemical & Engineering News
Volume 88 Issue 21 | p. 32 | Concentrates
Issue Date: May 24, 2010

Rapid Water-Ion Dynamics Revealed

New spectroscopic techniques provide femtosecond details of water-ion interactions in solution
Department: Science & Technology
Keywords: water, hydrogen bonds, ions, dynamics
In this representation, a hydrated cation (green) and hydrated anion (blue) trap the hydrogen-bonded network of water molecules that exists between them.
Credit: Amolf/XKP
8821scon_tielrooij2HRc_opt
 
In this representation, a hydrated cation (green) and hydrated anion (blue) trap the hydrogen-bonded network of water molecules that exists between them.
Credit: Amolf/XKP

New spectroscopic techniques are providing some of the most detailed pictures yet of the behavior of water molecules on femtosecond time­scales (Science 2010, 328, 1003 and 1006). Ubiquitous liquid water, with its networks of evanescent hydrogen bonds and its vital interactions with biological and atmospheric molecules and ions, remains mysterious. In one study, Minbiao Ji of the SLAC National Accelerator Laboratory and colleagues used two-dimensional infrared spectroscopy to verify a recent prediction that when water molecules and perchlorate ions (ClO4 ) exchange hydrogen bonds, the water molecules rotate in quick jumps rather than in smooth motions. In a separate study, Klaas-Jan Tielrooij and colleagues at the Institute for Atomic & Molecular Physics, in Amsterdam, employed terahertz dielectric relaxation spectroscopy and femtosecond infrared pump-probe spectroscopy to discover that some cation-anion combinations in water, such as magnesium and sulfate, can impede the motions of water molecules at relatively long ranges. “These and related studies herald a new era in our understanding of solvation dynamics in aqueous solutions,” writes University of Wisconsin, Madison, theoretical chemist James L. Skinner in a commentary about the two studies.—EKW

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

Leave A Comment

*Required to comment