Direct Measurement of Long-Range van der Waals Forces

Nature ◽  
1956 ◽  
Vol 178 (4546) ◽  
pp. 1339-1340 ◽  
Author(s):  
A. P. PROSSER ◽  
J. A. KITCHENER
Keyword(s):  
Long Range ◽  
Direct Measurement ◽  
Van Der Waals ◽  
Van Der Waals Forces

scholarly journals Tuning adlayer-substrate interactions of graphene/h-BN heterostructures on Cu(111)–Ni and Ni(111)–Cu surface alloys

RSC Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1916-1927
Author(s):  
Jianmei Huang ◽  
Qiang Wang ◽  
Pengfei Liu ◽  
Guang-hui Chen ◽  
Yanhui Yang
Keyword(s):  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Alloy Surface ◽  
Surface Alloys ◽  
Substrate Interactions

The evolution of the interface and interaction of h-BN and graphene/h-BN (Gr/h-BN) on Cu(111)–Ni and Ni(111)–Cu surface alloys versus the Ni/Cu atomic percentage on the alloy surface were comparatively studied by DFT-D2, including critical long-range van der Waals forces.

Computer Simulation of Colloidal Aggregation Induced by Directionalism of Long Range van der Waals Forces

2007 ◽  
Vol 23 (08) ◽  
pp. 1241-1246 ◽  
Author(s):  
XIONG Hai-Ling ◽  
◽  
◽  
YUAN Yong-Zhi ◽  
LI Hang ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Colloidal Aggregation

The direct measurement of normal and retarded van der Waals forces

1969 ◽  
Vol 312 (1511) ◽  
pp. 435-450 ◽  
Keyword(s):  
Direct Measurement ◽  
Contact Region ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Surface Forces ◽  
Direct Measure ◽  
Rigid Support ◽  
Critical Separation ◽  
20 Nm ◽  
Multiple Beam Interferometry

A direct measurement has been made of the forces in air between two cylindrical sheets of mica arranged with their axes mutually at right angles. The contact resembles that between a sphere and a flat. The mica sheets are glued to glass formers, their concave face being first slightly silvered. The contact region and the distance of approach are measured by multiple beam interferometry using fringes of equal chromatic order (f. e. c. o.). This gives an accuracy for the distances between the surfaces of ± 0.3 nm. Since the surfaces are molecularly smooth it is possible to bring them very close to one another. One surface is held on a rigid support, the other on a light cantilever beam. The surfaces are slowly brought together and at a critical separation ‘flick’ together. The ‘flick’ distance depends on the stiffness of the cantilever and this in turn provides a direct measure of the surface forces. By using cantilevers of different stiffnesses the method has proved effective for separations ranging from 5 to 30 nm. The results show that for separations less than about 10 nm the forces operating are ‘normal’ van der Waals forces whilst for distances greater than 20 nm they are ‘retarded’ van der Waals forces.

On the measurability of long range van der Waals forces between protons

1975 ◽  
Vol 55 (2) ◽  
pp. 147-148 ◽  
Author(s):  
A.O. Barut ◽  
J. Nagel
Keyword(s):  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces

ON THE STRONG VAN DER WAALS FORCES BETWEEN HADRONS DUE TO CONFINING POTENTIALS

1987 ◽  
Vol 02 (01) ◽  
pp. 265-272 ◽  
Author(s):  
A. O. BARUT ◽  
R. RACZKA
Keyword(s):  
Long Range ◽  
Bound States ◽  
Degrees Of Freedom ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Color Singlet ◽  
Singlet States ◽  
Color Scheme

The problem of long range forces between hadrons is re-examined. Without color degrees of freedom the confining potentials lead to unacceptably large van der Waals forces. The color degrees of freedom are investigated in the case of mesons taking into account both of the color singlet states of four constituents. The consistency of the color scheme requires the existence of four-quark bound states as well as two separate mesons and puts still restrictions on the confining potentials.

Direct measurement of the long-range van der Waals forces

1957 ◽  
Vol 242 (1230) ◽  
pp. 403-409 ◽  
Keyword(s):  
Experimental Method ◽  
Long Range ◽  
Direct Measurement ◽  
White Light ◽  
Van Der Waals ◽  
Flat Glass ◽  
Dispersion Force ◽  
Electrostatic Charges ◽  
Electrical Capacity ◽  
Capacity Method

There exists a serious discrepancy in published values for the directly determined van der Waals force between macroscopic bodies, the results of Derjaguin & Abricossova (1951–56) being smaller by a factor of approximately 500 than those of Overbeek & Sparnaay (1951–54). This could have important implications in the quantitative theory of colloids. Some independent determinations have therefore been carried out to resolve this anomaly. Determinations of the force of attraction between parallel, optically flat glass plates in vacuo have been carried out at distances of separation ranging from 0∙7 to 1∙2 μ . The method was similar in principle to that of Overbeek & Sparnaay but of improved sensitivity. The force, which ranged from 10 –2 to 10 –3 dyn cm –2 , was determined by measuring the deflexion of a spring, using an electrical capacity method; the distance between the plates was obtained from interference colours produced from the reflexion of white light. Particular attention was paid to elimination of any effect of electrostatic charges on the plates. The results definitely confirm the work of Derjaguin & Abricossova. The agreement is particularly satisfactory in that a different experimental method was employed, with bodies of different shape and with different methods of discharging the plates. Further, the results prove that the retarded dispersion force is operative at the above distances.

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