Counterion evaporation
We study the adsorption behavior of a highly charged rodlike polyelectrolyte approaching an oppositely charged planar wall in an unbounded electrolyte solution. The grand potential, the entropy, and the total number of screening particles are calculated as functions of the rod-wall distance, using input parameters that are typical of a DNA-molecule and charged lipid bilayers. It is found that counterions which are bound to the polyelectrolyte at infinite rod-wall distances will be released, or {open_quotes}evaporated,{close_quotes} as the DNA molecule moves closer to the charged wall. This effect can be regarded as the opposite of the ion-condensation process. The transition of ions from the system of screening ions into the reservoir of bulk ions can lead to an increase of the enthalpy. This gain of enthalpy for the whole system manifests itself as an attractive contribution to the effective interaction between the wall and the polyelectrolyte.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40203320
- Journal Information:
- Physical Review E, Journal Name: Physical Review E Journal Issue: 6 Vol. 63; ISSN 1063-651X
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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