Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems

Aqueous reverse micelles, which are surfactant aggregates in nonpolar solvents that enclose packets of aqueous solution, have been widely studied experimentally and theoretically, but much remains unknown about the properties of water in the interior. The few previous molecular dynamics simulations of reverse micelles have not examined how the micelle size affects these properties. We have modeled the interior of an aqueous reverse micelle as a rigid spherical cavity, treating only the surfactant headgroups and water at a molecular level. Interactions between the interior molecules and the cavity are represented by a simple continuum potential. The basic parameters of the modelmicelle size, surface ion density, and water contentare based on experimental measurements of Aerosol OT reverse micelles but could be chosen to match other surfactant systems as well. The surfactant head is modeled as a pair of atomic ions:  a large headgroup ion fixed at the cavity surface and a mobile counterion. The SPC/E model ...

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Molecular Dynamics Simulations of the Interior of Aqueous Reverse Micelles

Although water is often hailed as the lubricant of life, a detailed understanding of its role in many chemical and biological processes still eludes us. In many natural systems, water is confined in an environment where its free movement is restricted and its three-dimensional hydrogen-bonded network is disrupted. Very recently, several groups applied ultrafast laser spectroscopy to study the dynamics of the constrained water molecules. It is observed that the dynamic behavior of the confined water molecules is markedly different from that of the ordinary water molecules. The most striking result is the bimodal response of confined water, with one bulk water-like subpicosecond component and a much slower component in a time scale of hundreds or thousands of picoseconds. This slow second component constitutes 10−30% of the total response and is crucial in the understanding of the role of water in complex chemical and biological processes. The origin of the slow component has been a subject of intense recen...

Slow dynamics of constrained water in complex geometries

Photon echo spectroscopy is used to study the mechanisms of solvation dynamics in protein environments at room temperature. Ultrafast and additional multi-exponential long time scales are observed in the three-pulse photon echo peak shift data of the fluorescein dye eosin bound to lysozyme in aqueous solution. The dynamics of the solvated lysozyme are characterized with dielectric continuum models that integrate dielectric data for water with that for lysozyme. By comparing our data with previous results for eosin in water [Lang, M. J.; Jordanides, X. J.; Song, X.; Fleming, G. R. J. Chem. Phys. 1999, 110, 5584], we find that the total coupling of the electronic transition frequency of eosin to the nuclear motions of the aqueous lysozyme solution is smaller than in the aqueous solution. On an ultrafast time scale, solvation appears to be dominated by the surrounding water and not by the ultrafast internal motions of lysozyme. However, over long time scales, lysozyme does contribute significantly, either di...

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1859&context=chem_pubs

Solvation Dynamics in Protein Environments Studied by Photon Echo Spectroscopy

Interactions of small molecules with reverse micelles

Terahertz spectroscopy of water in inverse micelles

A thick holographic recording medium suitable for use in multiplex holography is prepared from a solution of a bi-functional oligomer and a mono-functional monomer. Precuring, possibly at the same radiation wavelength used for recording, cross-links the oligomer, thereby creating a host for the recording monomer.

Photo recording medium

Photopolymers are attractive candidates for high-density holographic data storage because of their high sensitivity and refractive index contrast. We have incorporated several high-index organic monomers into high optical quality acrylate oligomer-based formulations. Using reactivity ratios, reaction kinetics, and component refractive indices as guidelines, a 6-fold increase in Δn has been achieved compared to an initial all-acrylate formulation. Samples prepared from these formulations have been used to write and read >200 high-quality holograms in a given volume of material. This is the first time a photopolymeric medium has successfully been used to multiplex this number of holograms. Using these resins, a protocol for the evaluation of photopolymers as holographic media has been developed.

Acrylate Oligomer-Based Photopolymers for Optical Storage Applications

High storage densities using a holographic system are achievable using a stratified medium while maintaining a relatively high selectivity upon reconstruction of the stored images. Such combination of high density and high selectivity is achievable by employing a stratified medium and a recording process where selectivity does not vary with recording thickness.

Holographic process and media therefor

of EP0824222A thick holographic recording medium suitable for use in multiplex holography is prepared from a solution of a bi-functional oligomer and a monofunctional monomer Precuring, possibly at the same radiation wavelength used for recording, cross-links the oligomer, thereby creating a host for the recording monomer

Vicki L. Colvin

Papers

Terahertz spectroscopy of water in inverse micelles

Photo recording medium

Acrylate Oligomer-Based Photopolymers for Optical Storage Applications

Holographic process and media therefor

Photorecording medium and method