Volume 123, Issue 21, 01 December 2005
Index of content:
Postcollision interaction in noble gas clusters: Observation of differences in surface and bulk line shapes123(2005); http://dx.doi.org/10.1063/1.2135771View Description Hide Description
The surface and bulk components of the x-rayphotoelectron spectra of free noble gas clusters are shown to display differences in the influence of postcollision interaction between the photoelectron and the Auger electron on the spectral line shape; the bulk component is observed to be less affected than the surface and atomic parts of the spectra. A model for postcollision interaction in nonmetallic solids and clusters is also provided which takes the polarization screening into account. Core-level photoelectron spectra of Ar, Kr, and Xe have been recorded to verify the dependence of the postcollision interaction effect on the polarizability of the sample.
A new method to reconstruct three-dimensional spatial distribution function from radial distribution function in solvation structure123(2005); http://dx.doi.org/10.1063/1.2137695View Description Hide Description
Three-dimensional spatialdistribution function (SDF) of solvent is a fundamental quantity for analysis of solvation. However, its calculation has been very limited because long computational time is required. We here developed a novel and robust method to construct approximated SDFs of solvent sites from radial distribution functions. In this method, the expansion of SDFs in real solid harmonics around atoms of solute leads to a linear equation, from which SDFs are evaluated with reasonable computational time. This method is applied to the analysis of the solvation structure of liquid water, as an example. The successful results clearly show that this method is very powerful to investigate solvation structure.
123(2005); http://dx.doi.org/10.1063/1.2133728View Description Hide Description
Ab initio molecular-dynamic simulations using density-functional theory and the recent atom-centered density-matrix propagation (ADMP) method were used to study the bond breaking and formation for a case-study substitution nucleophilic bimolecular reaction, namely, the Walden inversion. Using the atoms-in-molecule approach, we have performed a detailed analysis to investigate intra- and intermolecular charge transfer along the ADMP trajectory. These results were compared to those obtained considering a static approach, such as the intrinsic reaction path. In particular, the topological properties computed along the dynamic trajectory well evidence a stronger electron exchange tending to spontaneously maximize the rising covalent interaction. Furthermore, their analysis suggests that the bond formation mechanism involves a reactive intermediate with a bonding interaction stronger than in the final product.
123(2005); http://dx.doi.org/10.1063/1.2138699View Description Hide Description
The translational diffusion coefficient of lipids located in the outer and inner leaflets of planar supported DLPC (1,2-dilauroyl-sn-glycero-3-phosphocholine) bilayers in the fluid phase was measured using fluorescencecorrelation spectroscopy of dye-labeled lipids at the low concentration of 0.001% and using iodide quenching of dyes in the outer leaflet to distinguish diffusion in the inner leaflet from that in the outer leaflet. To confirm the generality of these findings, the bilayers were prepared not only by vesicle fusion but also by Langmuir–Blodgett deposition. We conclude that regardless of whether the bilayers were supported on quartz or on a polymer cushion, in the inner and outer leaflets was the same within an experimental uncertainty of but with a small systematic tendency to be slower (by ) within the inner leaflet.
123(2005); http://dx.doi.org/10.1063/1.2141562View Description Hide Description
The oxidationreaction dynamics of a saturated hydrocarbon radical -butyl leading to the isobutene (, 1, 2) products in the gas phase were first investigated by applying a combination of high-resolution spectroscopy in a crossed-beam configuration and ab initio calculations. By comparing the nascent OH populations with the statistical theory, the reaction mechanism at the molecular level can be described in terms of two competing dynamic pathways: the major direct abstraction process leading to the inversion of vibrational populations, and the minor short-lived addition-complex process for hot rotational distributions.