Anisotropic dispersion forces in methane mixtures

1989 ◽  
Vol 68 (4) ◽  
pp. 853-865 ◽  
Author(s):  
P.W. Fowler ◽  
P. Lazzeretti ◽  
R. Zanasi
Keyword(s):  
Dispersion Forces ◽  
Anisotropic Dispersion

PHONON-INDUCED ANISOTROPIC DISPERSION FORCES ON A METALLIC SUBSTRATE

Nano LIFE ◽  
2012 ◽  
Vol 02 (02) ◽  
pp. 1240001 ◽  
Author(s):  
JE-LUEN LI ◽  
HANNES C. SCHNIEPP ◽  
ILHAN A. AKSAY ◽  
ROBERTO CAR
Keyword(s):  
Dielectric Response ◽  
Orientational Order ◽  
Metallic Substrate ◽  
Numerical Calculations ◽  
Dispersion Forces ◽  
Cetyltrimethylammonium Chloride ◽  
Surfactant Micelles ◽  
Crystalline Substrate ◽  
Ionic Contribution ◽  
Anisotropic Dispersion

Surfactant micelles (cetyltrimethylammonium chloride) adsorbed on Au(111) exhibit orientational order dictated by the gold crystal axes. To explain this phenomenon, we take into account the ionic contribution to the dielectric response of the metal. Since the motion of an ion inside the metallic lattice is restricted by its neighbors in an anisotropic way, the total dielectric response of the metal acquires directional dependence. A crystalline substrate is thus able to generate both torque and attraction on geometrically asymmetric objects. Numerical calculations show that the resulting anisotropic van der Waals force is indeed capable of orienting rod-like dielectric micelles on a Au(111) surface.

CALCULATION OF THE PRESSURE BROADENING OF ROTATIONAL RAMAN LINES DUE TO MULTIPOLAR AND DISPERSION INTERACTION

1966 ◽  
Vol 44 (10) ◽  
pp. 2411-2430 ◽  
Author(s):  
C. G. Gray ◽  
J. Van Kranendonk
Keyword(s):  
Cross Sections ◽  
Rotational Quantum Number ◽  
Dispersion Forces ◽  
Line Broadening ◽  
Molecular Constants ◽  
Fourth Degree ◽  
Impact Theory ◽  
Experimental Values ◽  
Anisotropic Dispersion ◽  
The Impact

The impact theory of Raman line broadening is applied to the broadening of the rotational Raman lines of diatomic molecules arising from electric multipole and anisotropic dispersion forces. Expressions are derived for the elastic and inelastic optical cross sections, and these are evaluated for the self-broadening in N2, O2, CO, and CO2, using values of the molecular constants obtained from sources independent of the line-broadening experiments. Included in the calculations are the "time", or "resonant", factors in the optical cross sections, and the resulting time integrals are explicitly evaluated for arbitrary multipole interactions, and anisotropic dispersion forces of second and fourth degree in the orientations. The overall agreement between the theoretical and experimental values of the magnitude of the half-widths is satisfactory, but a discrepancy appears in the variation of the broadening with the rotational quantum number. Possible explanations of this discrepancy are suggested in view of the results on foreign-gas broadening by monatomic gases.

Effect of dispersion forces on the potential of charged interfaces

2004 ◽  
Vol 306 (1-3) ◽  
pp. 209-217 ◽  
Author(s):  
Stefan Woelki ◽  
Hans-Helmut Kohler
Keyword(s):  
Dispersion Forces

VIBRATIONAL FREQUENCY PERTURBATIONS IN THE RAMAN SPECTRUM OF COMPRESSED GASEOUS HYDROGEN

1964 ◽  
Vol 42 (6) ◽  
pp. 1058-1069 ◽  
Author(s):  
A. D. May ◽  
G. Varghese ◽  
J. C. Stryland ◽  
H. L. Welsh
Keyword(s):  
Raman Band ◽  
Intermolecular Forces ◽  
Hydrogen Gas ◽  
High Spectral Resolution ◽  
Intermolecular Potential ◽  
Dispersion Forces ◽  
Frequency Shifts ◽  
Linear Coefficient ◽  
Relative Population ◽  
Good Agreement

The frequencies of the Q(J) lines of the fundamental Raman band of compressed hydrogen gas were measured with high spectral resolution for a series of densities from 25 to 400 Amagat units at 300 °K and 85 °K. The frequency shifts are expressed as a power series in the gas density. The linear coefficient at a given temperature has the form aJ = ai + ae(nJ/n), where ai, constant for all the Q lines, can be interpreted in terms of isotropic intermolecular forces, and ae(nJ/n), proportional to the relative population of the initial J level, arises from the inphase coupled oscillation of pairs of molecules. The temperature variation of ai is analyzed on the basis of the Lennard-Jones intermolecular potential and the molecular pair distribution function. The repulsive overlap forces and the attractive dispersion forces give, respectively, positive and negative contributions to ai, which can be characterized by the empirical parameters Krep and Katt. The values of Katt and ae are in good agreement with calculations based on the polarizability model of the dispersion forces. The relation of the results to the Raman frequency shifts in solid hydrogen is discussed.

Generalized theory of dispersion forces

1989 ◽  
Vol 20 (7) ◽  
pp. 735-747 ◽  
Author(s):  
Peter Görner ◽  
Josef Pich
Keyword(s):  
Dispersion Forces

scholarly journals WHY SCREENING EFFECTS DO NOT INFLUENCE THE CASIMIR FORCE

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1721-1742 ◽  
Author(s):  
V. M. MOSTEPANENKO ◽  
R. S. DECCA ◽  
E. FISCHBACH ◽  
B. GEYER ◽  
G. L. KLIMCHITSKAYA ◽  
...  
Keyword(s):  
Casimir Force ◽  
Charge Carriers ◽  
Reflection Coefficients ◽  
Dispersion Forces ◽  
Physical Reason ◽  
Lifshitz Theory ◽  
Third Law Of Thermodynamics ◽  
Applicability Condition ◽  
And Diffusion

The Lifshitz theory of dispersion forces leads to thermodynamic and experimental inconsistencies when the role of drifting charge carriers is included in the model of the dielectric response. Recently modified reflection coefficients were suggested that take into account screening effects and diffusion currents. We demonstrate that this theoretical approach leads to a violation of the third law of thermodynamics (Nernst's heat theorem) for a wide class of materials and is excluded by the data from two recent experiments. The physical reason for its failure is explained by the violation of thermal equilibrium, which is the fundamental applicability condition of the Lifshitz theory, in the presence of drift and diffusion currents.

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