Determination of van der Waals forces in monolayer films of lipids & biopolymers. Equation of state for two-dimensional films

1994 ◽  
Vol 272 (8) ◽  
pp. 1000-1004 ◽  
Author(s):  
K. S. Birdi ◽  
F. Madsen ◽  
K. Eberth
Keyword(s):  
Equation Of State ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Two Dimensional ◽  
Monolayer Films

4. States of matter

2014 ◽  
pp. 51-69
Author(s):  
Peter Atkins
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Liquid Crystals ◽  
Magnetic Resonance ◽  
Equation Of State ◽  
Soft Matter ◽  
Van Der Waals ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Van Der Waals Equation ◽  
Intermediate States

‘States of matter’ describes the three traditional states — gas, liquid, and solid — and the models used to predict and understand their behaviour. The van der Waals equation of state captures many of the properties of real gases. The classical way of studying the motion of molecules in liquids is to measure its viscosity. Techniques include neutron scattering and nuclear magnetic resonance. X-ray diffraction is used to determine the structures of solids. Intermediate states of matter — where liquid meets gas and liquid meets solid — are also considered. Examples include supercritical fluids, soft matter such as liquid crystals, and graphene, a remarkable and essentially two-dimensional material.

II.—The Van der Waals Force between a Proton and a Hydrogen Atom

1941 ◽  
Vol 61 (1) ◽  
pp. 20-25 ◽  
Author(s):  
C. A. Coulson
Keyword(s):  
Hydrogen Atom ◽  
Power Series ◽  
Interaction Energy ◽  
Van Der Waals ◽  
Ground States ◽  
Van Der Waals Forces ◽  
Van Der Waals Force ◽  
Hydrogen Atoms ◽  
Nuclear Separation

The calculation of Van der Waals forces has acquired considerable interest recently through the work of Buckingham, Knipp and others (Buckingham, 1937; Knipp, 1939). In these papers the interaction energy between two atoms is expressed as a power series in i/R, where R is the nuclear separation, and the various terms in this series are known as dipole-dipole, dipole-quadrupole, quadrupole-quadrupole, etc… interactions. In most cases only approximate values are obtainable for the coefficients in this series, though for two hydrogen atoms in their ground states, Pauling and Beach (1935) have determined the magnitudes correct to about I in 106. In this paper we discuss the simplest possible problem of this nature, i.e. the force between a bare proton and a normal unexcited hydrogen atom. We shall show that a rigorous determination of the coefficients in the power series can be made.

Generalized van der Waals theory. IV. Variational determination of the hard-sphere diameter

1981 ◽  
Vol 34 (9) ◽  
pp. 1809 ◽  
Author(s):  
MA Hooper ◽  
S Nordholm
Keyword(s):  
Equation Of State ◽  
Hard Sphere ◽  
Pair Correlation ◽  
Van Der Waals ◽  
Critical Parameters ◽  
Variational Parameter ◽  
Sphere Diameter ◽  
Entropy Functional ◽  
Van Der Waals Theory

The generalized van der Waals theory is here extended by incorporating the hard-sphere diameter as a variational parameter. Moreover, the entropy functional has been chosen so as to accurately reflect the density dependence of the excluded volume revealed by the hard-sphere equation of state. The combined effect of these two improvements yields a theory capable of describing the equation of state of the Lennard- Jones model of classical fluids to an accuracy comparable to that of the pair correlation theories. The results presented here include critical parameters and coexistence and vapour pressure curves.

Determination of van der Waals Forces

Nature ◽  
1936 ◽  
Vol 138 (3480) ◽  
pp. 77-77 ◽  
Author(s):  
H. S. W. MASSEY ◽  
R. A. BUCKINGHAM
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Forces

On physical adsorption XVII. Experimental verification of the two-dimensional van der Waals equation of state above and below the critical temperature

1962 ◽  
Vol 265 (1323) ◽  
pp. 455-462 ◽  
Keyword(s):  
Critical Temperature ◽  
Carbon Tetrachloride ◽  
Equation Of State ◽  
Adsorption Isotherms ◽  
Physical Adsorption ◽  
Van Der Waals ◽  
Phase Changes ◽  
Two Dimensional ◽  
Van Der Waals Equation ◽  
Surface Field

Adsorption isotherms of carbon tetrachloride, chloroform and fiuorotrichloromethane on a substrate of graphitized carbon are reported at temperatures between 200 and 300 °K. Evidence is presented that at these temperatures the residual heterogeneity of the substrate is not observed: under these conditions the true equation of state of the adsorbed film can be deduced directly from the measured adsorption isotherms. All the data reported are described by the adsorption isotherm equation corresponding to a two-dimensional van der Waals gas; this description continues to apply at temperatures where the isotherms show discontinuities characteristic of first-order phase changes. The two-dimensional critical temperature of each of the adsorbed films is rather less than the value predicted by the two dimensional van der Waals equation; this is taken as evidence for the polarization of the adsorbate molecules by an electric field present at the graphite surface. The results obtained with the isotropic carbon tetrachloride molecule indicate a surface field of 1 x 10 5 e. s. u./cm 2 ; we deduce that the anisotropic adsorbates should be oriented at the interface, with the axis of the permanent dipole alined with the surface field.

scholarly journals Free paths and transport phenomena in gases and the quantum theory of collisions. II.—The determination of the laws of force between atoms and molecules

1934 ◽  
Vol 144 (851) ◽  
pp. 188-205 ◽  
Keyword(s):  
Quantum Theory ◽  
Perturbation Method ◽  
Transport Phenomena ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Range Interaction ◽  
First Approximation ◽  
Diffusion Phenomena ◽  
The Law

The quantum theory has provided a means of calculating the interaction energies of two atoms by a perturbation method. It appears that, the short range interaction forces are due mainly to electron exchange phenomena between the two atoms, while the van der Waals forces arise from mutual polarization effects. The theory gives the first of these forces in the first approximation, while the van der Waals forces appear only in the second approximation, At large distances, where the interaction is small, it is somewhat surprising that the first approximation is not sufficient, and one is led to doubt the accuracy of the method when applied at distances at which the first and second approximations give comparable results. At these distances the mutual potential energy is comparable with the mean kinetic energy of a gas atom at ordinary temperatures, and it is therefore clear that a study of gas-kinetic collision phenomena should provide a satisfactory test of the validity of the perturbation method in this region. It is the object of this paper to carry out a number of calculations with this aim in view. In a previous paper the quantum theory of collisions was applied to gas-kinetic collisions, and it was shown that, although the classical theory can be used with accuracy to determine the law of force from viscosity and diffusion phenomena associated with heavy gases, it cannot he applied with safety to hydrogen and helium. The method to he used in such cases was given, and it was also shown that the existence of a definite total collision area—a feature of the quantum theory of scattering by a centre of force, the potential of which falls of more rapidly than r -2 at large distances—provides a further means of determining the law of force. As this collision area can now be directly measured with accuracy by molecular ray experiments, the range of applicability of tins method is considerably greater than that of methods based on transport phenomena.

Monolayer films of retinal. Equation of state for two-dimensional films

Langmuir ◽  
1991 ◽  
Vol 7 (12) ◽  
pp. 3174-3175 ◽  
Author(s):  
K. S. Birdi
Keyword(s):  
Equation Of State ◽  
Two Dimensional ◽  
Monolayer Films

Determination of band alignment in two-dimensional h-BN/WS2 van der waals heterojunction by X-ray photoelectron spectroscopy

2021 ◽  
Vol 854 ◽  
pp. 157301
Author(s):  
Shu’an Xing ◽  
Guijuan Zhao ◽  
Yan Xu ◽  
Jie Wang ◽  
Xunshuan Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Van Der Waals ◽  
Band Alignment ◽  
Two Dimensional ◽  
X Ray
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