scholarly journals Spectral mixing formulations for van der Waals–London dispersion interactions between multicomponent carbon nanotubes

2008 ◽  
Vol 104 (5) ◽  
pp. 053513 ◽  
Author(s):  
Rick Rajter ◽  
Roger H. French ◽  
Rudi Podgornik ◽  
W. Y. Ching ◽  
V. Adrian Parsegian
Keyword(s):  
Carbon Nanotubes ◽  
Van Der Waals ◽  
Dispersion Interactions ◽  
London Dispersion ◽  
Spectral Mixing

scholarly journals Optical Properties and van der Waals-London Dispersion Interactions in Inorganic and Biomolecular Assemblies

2014 ◽  
Vol 1619 ◽  
Author(s):  
Daniel M. Dryden ◽  
Yingfang Ma ◽  
Jacob Schimelman ◽  
Diana Acosta ◽  
Lijia Liu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectroscopic Ellipsometry ◽  
Density Functional ◽  
Type I Collagen ◽  
Strong Dependence ◽  
Van Der Waals ◽  
Fundamental Absorption Edge ◽  
Type I ◽  
Dispersion Interactions ◽  
London Dispersion

ABSTRACTThe optical properties and electronic structure of AlPO4, SiO2, Type I collagen, and DNA were examined to gain insight into the van der Waals-London dispersion behavior of these materials. Interband optical properties of AlPO4 and SiO2 were derived from vacuum ultraviolet spectroscopy and spectroscopic ellipsometry, and showed a strong dependence on the crystals’ constituent tetrahedral units, with strong implications for the role of phosphate groups in biological materials. The UV-Vis decadic molar absorption of four DNA oligonucleotides was measured, and showed a strong dependence on composition and stacking sequence. A film of Type I collagen was studied using spectroscopic ellipsometry, and showed a characteristic shoulder in the fundamental absorption edge at 6.05 eV. Ab initio calculations based on density functional theory corroborated the experimental results and provided further insights into the electronic structures, interband transitions and vdW-Ld interaction potentials for these materials.

scholarly journals Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

2007 ◽  
Vol 60 (4) ◽  
pp. 251 ◽  
Author(s):  
Roger H. French ◽  
Karen I. Winey ◽  
Min K. Yang ◽  
Weiming Qiu
Keyword(s):  
Free Energy ◽  
Optical Properties ◽  
Surface Free Energy ◽  
Vacuum Ultraviolet ◽  
Van Der Waals ◽  
Interband Transitions ◽  
Dispersion Interactions ◽  
Dispersion Component ◽  
London Dispersion ◽  
Hamaker Constants

The interband optical properties of polystyrene in the vacuum ultraviolet (VUV) region have been investigated using combined spectroscopic ellipsometry and VUV spectroscopy. Over the range 1.5–32 eV, the optical properties exhibit electronic transitions we assign to three groupings, E1, E2, and E3, corresponding to a hierarchy of interband transitions of aromatic (π → π*), non-bonding (n → π*, n → σ*), and saturated (σ → σ*) orbitals. In polystyrene there are strong features in the interband transitions arising from the side-chain π bonding of the aromatic ring consisting of a shoulder at 5.8 eV (E1′) and a peak at 6.3 eV (E1), and from the σ bonding of the C–C backbone at 12 eV (E3′) and 17.1 eV (E3). These E3 transitions have characteristic critical point line shapes associated with one-dimensionally delocalized electron states in the polymer backbone. A small shoulder at 9.9 eV (E2) is associated with excitations possibly from residual monomer or impurities. Knowledge of the valence electronic excitations of a material provides the necessary optical properties to calculate the van der Waals–London dispersion interactions using Lifshitz quantum electrodynamics theory and full spectral optical properties. Hamaker constants and the van der Waals–London dispersion component of the surface free energy for polystyrene were determined. These Lifshitz results were compared to the total surface free energy of polystyrene, polarity, and dispersive component of the surface free energy as determined from contact angle measurements with two liquids, and with literature values. The Lifshitz approach, using full spectral Hamaker constants, is a more direct determination of the van der Waals–London dispersion component of the surface free energy of polystyrene than other methods.

scholarly journals Graded interface models for more accurate determination of van der Waals–London dispersion interactions across grain boundaries

2006 ◽  
Vol 74 (20) ◽  
Author(s):  
Klaus van Benthem ◽  
Guolong Tan ◽  
Roger H. French ◽  
Linda K. DeNoyer ◽  
Rudolf Podgornik ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Van Der Waals ◽  
Accurate Determination ◽  
Dispersion Interactions ◽  
Interface Models ◽  
London Dispersion

Calculating van der Waals-London dispersion spectra and Hamaker coefficients of carbon nanotubes in water from ab initio optical properties

2007 ◽  
Vol 101 (5) ◽  
pp. 054303 ◽  
Author(s):  
R. F. Rajter ◽  
R. H. French ◽  
W. Y. Ching ◽  
W. C. Carter ◽  
Y. M. Chiang
Keyword(s):  
Carbon Nanotubes ◽  
Optical Properties ◽  
Ab Initio ◽  
Van Der Waals ◽  
London Dispersion

Carbon Nanotubes in Arrays: Competition of van-der-Waals and Elastic Forces

2019 ◽  
Vol 64 (5) ◽  
pp. 218-221
Author(s):  
V. V. Smirnov ◽  
L. I. Manevitch
Keyword(s):  
Carbon Nanotubes ◽  
Van Der Waals ◽  
Elastic Forces

scholarly journals Impact of Van der Waals interactions on structural and nonlinear optical properties of azobenzene switches

2021 ◽  
Author(s):  
carmelo Naim ◽  
Frédéric Castet ◽  
Eduard Matito
Keyword(s):  
Density Functional ◽  
Nonlinear Optical ◽  
Van Der Waals Interactions ◽  
Dispersion Interactions ◽  
Geometrical Structures ◽  
Hartree Fock ◽  
Meta Position ◽  
Good Account ◽  
London Dispersion ◽  
Azobenzene Derivatives

<div> <div> <div> <p>The geometrical structures, relative Z-E energies, and second-order nonlinear responses of a collection of azobenzene molecules symmetrically substituted in meta- position with functional groups of different bulkiness are investigated using various ab initio and DFT levels of approximation. We show that RI-MP2 and RI-CC2 approximations provide very similar geometries and relative energies and evidence that London dispersion interactions existing between bulky meta-substituents stabilize the Z con- former. The !B97-X-D exchange-correlation functional provides an accurate description of these effects and gives a good account of the nonlinear optical response of the molecules. We show that density functional approximations should include no less than 50% of Hartree-Fock exchange to provide accurate hyperpolarizabilities. A property-structure analysis of the azobenzene derivatives reveals that the main contribution to the first hyperpolarizability comes from the azo bond, but phenyl meso-substituents can enhance it.</p> </div> </div> </div>

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