scholarly journals Pressure broadening of spectral lines and van der waals forces II—Continuous broadening and discrete bands in pure mercury vapour

1937 ◽  
Vol 158 (893) ◽  
pp. 230-241 ◽  
Keyword(s):  
Excited Atom ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Spectral Lines ◽  
Mercury Vapour ◽  
Pressure Broadening ◽  
Quantitative Investigation ◽  
Normal Atom ◽  
Low Pressures ◽  
Optical Impact

The spectrum of single transits, forming part of the pressure broadening, has been quantitatively investigated for Na—A and for Hg—A transits. It was found to be very nearly identical with the occurrence distribution of the perturbed eigenfrequencies, the intensity distribution being in agreement with the theoretical prediction I( v ) ~ Δ v -3/2 within the limits of its validity. As this agreement is a direct experimental test on the sixth power potential law of the van der Waals forces, given by London’s wave mechanical theory, it seemed to be of interest to investigate a case in which the velocity of the atoms is considerably less, so that any possible influence of the motion is smaller still. The interaction between two mercury atoms, i. e ., the broadening of the mercury resonance line by the mercury pressure itself, was therefore chosen for quantitative investigation. An excited atom interacts with a normal atom of the same kind at very large distances with a potential of force proportional to 1/ r 3 is the internuclear distance. The influence of this “resonance force” on pressure broadening has been treated theoretically by Weisskopf. Though it is considerable at very low pressures, resulting in large “optical impact diameters” for the Lorentz effect, it is very small at higher densities. This is connected with the dipole property of the forces: the interactions of several neighbouring atoms mainly cancel each other, leaving a very small residue only, the so-called coupling broadening. It was thus expected! that in the wing effect the resonance forces can be completely neglected.

scholarly journals Pressure broadening of spectral lines and van der Waals forces I—Influence of argon on the mercury resonance line

1937 ◽  
Vol 158 (893) ◽  
pp. 212-229 ◽  
Keyword(s):  
Spectral Line ◽  
Intensity Distribution ◽  
Resonance Line ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Spectral Lines ◽  
Molecular Spectra ◽  
Pressure Broadening ◽  
Single Atoms ◽  
Intensity Measurements

It is the purpose of this and the following paper to consider the type of broadening of a spectral line, produced by approaches of other atoms to the radiating atom, which we shall call throughout “transits". The aspect with which we are particularly concerned is the transits of single atoms producing the wing of the broadened line. The intensity distribution in spectra of this type, which are intermediate between ordinary pressure broadening and continuous molecular spectra, can be interpreted in a simple way, yielding results on the van der Waals forces. The first paper gives an account of intensity measurements in the single transit region of the mercury line 2537 A. broadened by the admixture of argon.

Self-Assembly of a Chiral Cubic Three-Connected Net from the High Symmetry Molecules C60 and SnI4

2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava
Keyword(s):  
Organic Synthesis ◽  
Self Assembly ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
High Symmetry ◽  
Molecular Chirality ◽  
Chiral Materials ◽  
Self Assembled ◽  
Chiral Centers

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.

scholarly journals Nanotube‐Based 1D Heterostructures Coupled by van der Waals Forces

Small ◽  
2021 ◽  
pp. 2102585
Author(s):  
Sofie Cambré ◽  
Ming Liu ◽  
Dmitry Levshov ◽  
Keigo Otsuka ◽  
Shigeo Maruyama ◽  
...  
Keyword(s):  
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.

Condensation energies for metals on glass and other substrates

1959 ◽  
Vol 252 (1270) ◽  
pp. 418-430 ◽  
Keyword(s):  
Sodium Chloride ◽  
Single Crystal ◽  
Physical Adsorption ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Potassium Bromide ◽  
Binding Energies ◽  
Adhesive Energy ◽  
Good Agreement

Earlier work on condensation phenomena is briefly reviewed, and existing measurements of condensation energies are summarized. Measurements of condensation energies have been made for aluminium, silver and cadmium on glass and for aluminium and silver on single-crystal cleavage surfaces of sodium chloride and potassium bromide. Adhesive energies or binding energies between film and substrate have been calculated in each case. Association energies for nucleation are obtained by difference and shown to be consistent. Results for cadmium show good agreement with earlier work, but results for aluminium do not agree with the earlier results of Rhodin who measured the condensation energies for aluminium on various substrates, obtaining values which suggest chemisorption. These results appear to be too high and a possible explanation is given. It is concluded that the adhesive energy is due to physical adsorption and can be explained in terms of van der Waals forces only.

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