Debye-Huckel screening length

The hydrodynamic radius for each particle was taken to be 0.5 K. q = elementary charge unit. Solvent dielectric e = 80. A time step of 0.001 ps was used k = inverse Debye-Huckel screening length. 

In view of the role one may presume for simple electrolyte - namely, its effect on the Debye-Huckel screening length - a dependence of Ksec on 1-1/2 was anticipated (25). However, the ionic strength was adjusted not by eluant modification, but by varying sample concentration, so the failure of the data for NaPSS eluted in pure H2O to conform to the aforementioned linear dependence is difficult to interpret. 

The second feature is the screening parameter k which appears in the linearized Equation 5.77 and in the solution, Equation 5.79. Its reciprocal Vk is the characteristic range of the screened potential and is sometimes termed the Debye-Huckel screening length. It is composed of the following constants ... 

This equation cannot actually apply to a polyelectrolyte, but can be used to estimate entropy changes. The two charged segments join together through electrostatic attraction if and only if these come within a distance (say a) less than the Debye-Huckel screening length. The volume (Vj) of closest approach will be Vj X An 13. This leads to Jacobson-Stockmayer equation written for the present system as [20]... 

This theoretical expression was obtained for a charged chain with a Gaussian statistics in a solution with monovalent salt [33]. The chain was assumed to be of infinite length and the electrostatic interactions were treated at a linear level with a Debye-Huckel screened interaction between charges due to the presence of monovalent salts. This treatment neglects non-linear effects connected to counterion condensation, as well as chain-end effects present in our simulations. 

The classical approach to correct charge carrier interactions in liquid systems is the Debye-Huckel theory which is extensively discussed in textbooks.79 The decisive parameter is the screening length... 

The theoiy outlined above is a takeoff on the Debye Huckel theory of ionic solvation. In the electrochemistry literature it is known as the Gouy-Chapman theory. The Debye screening length is seen to depend linearly on ff and to decrease as (z+n+ +z zi ) /2 with increasing ionic densities. For a solution of monovalent salt, where z+ = z = 1 and = = n, this length is given by... 

A typical disjoining pressure variation with film thickness is shown in Figure 7a. At small thicknesses, a repulsive force is observed which can be fitted with an exponential form exp-(jch), as expected for screened electrostatic repulsion k is close to the calculated inverse Debye Huckel length in the solution ... 

Thus we have found that the screening should be more efficient than in the Debye Huckel theory. The Debye length /k is shorter by the factor yj 1 — k g2/2 due to the hard sphere holes cut in the Coulomb integrals which reduce the repulsion associated with counterion accumulation. A comparison with Monte Carlo simulation results [20] bears out this view of the ion size effect [19]. 

A key quantity in the Debye-Huckel theory, leading to the values of the constants A and B, is the screening length, k, the average reciprocal of the radius of the ionic atmosphere surrounding an ion in the solution, made up essentially by ions of the opposite charge. The square of this quantity is proportional to the ionic strength of the solution and also to the reciprocal of the product w T ... 

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