10 research outputs found
Salt-induced changes of colloidal interactions in critical mixtures
We report on salt-dependent interaction potentials of a single charged
particle suspended in a binary liquid mixture above a charged wall. For
symmetric boundary conditions (BC) we observe attractive particle-wall
interaction forces which are similar to critical Casimir forces previously
observed in salt-free mixtures. However, in case of antisymmetric BC we find a
temperature-dependent crossover from attractive to repulsive forces which is in
strong contrast to salt-free conditions. Additionally performed small-angle
x-ray scattering experiments demonstrate that the bulk critical fluctuations
are not affected by the addition of salt. This suggests that the observed
crossover can not be attributed alone to critical Casimir forces. Instead our
experiments point towards a possible coupling between the ionic distributions
and the concentration profiles in the binary mixture which then affects the
interaction potentials in such systems.Comment: 5 pages, 4 Figure
Theoretical study of chiral discrimination in the hydrogen bonding complexes of the hydrazine dimer
Solvent Effects on Vibronic Coupling in a Flexible Bichromophore: Electronic Localization and Energy Transfer induced by a Single Water Molecule
The calculation of thermodynamic properties of molecules
Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain such quantities by computation are quantum mechanical methods and group contribution methods. Although a lot of progress was made over the last decade, for the majority of chemical species we are still quite a bit away from what is often referred to as chemical accuracy, i.e. '1 kcal mol(-1)'. Currently, for larger molecules the combination of group contribution methods with group additive values that are determined with the best available computational ab initio methods seems to be a viable alternative to obtain thermodynamic properties near chemical accuracy. New developments and full use of existing tools may lead to further improvements ( critical review, 83 references)