Intercollisional interference effects in pressure-induced infrared spectra

1968 ◽  
Vol 46 (10) ◽  
pp. 1173-1179 ◽  
Author(s):  
J. Van Kranendonk
Keyword(s):  
Spectral Density ◽  
Infrared Spectra ◽  
Interference Effect ◽  
Dipole Moments ◽  
Intermolecular Force ◽  
Interference Effects ◽  
Anisotropic Part ◽  
Induced Dipole ◽  
Binary Collisions ◽  
Zero Frequency

The dip observed in the Q branch of the pressure-induced vibrational spectra at high densities is shown to be an interference effect due to the correlations existing between the dipole moments induced in successive binary collisions. A similar dip is predicted to exist in the translational spectra of inertgas mixtures at zero frequency. This intercollisional interference effect has the same origin as the dip in the spectral density of the intermolecular force, discussed by Purcell in connection with nuclear electric dipole relaxation. The effect does not occur for the anisotropic part of the induced dipole moments, and this explains the observed absence of any splitting of the S lines and of the QQ component of the Q branch of the induced infrared spectra.

Intercollisional interference at low temperatures

1985 ◽  
Vol 63 (1) ◽  
pp. 99-103
Author(s):  
John Courtenay Lewis
Keyword(s):  
Dipole Moment ◽  
Impact Parameter ◽  
Low Temperatures ◽  
Quantum Effect ◽  
Intermolecular Force ◽  
Fundamental Band ◽  
Induced Dipole ◽  
Binary Collisions

The intercollisional interference dip in the Q-branch of the fundamental band of collision-induced spectra of H2–He mixtures partially fills in at low temperatures. In contradiction to claims that this ia a quantum effect, we show 1. that if the induced dipole moment is exactly proportional to the intermolecular force then the interference dip goes to zero at all temperatures; 2. that the filling-in of the dip is essentially a classical phenomenon and is due mainly to the discontinuity in the distance of closest approach during binary collisions as a function of impact parameter.

Theory of Intercollisional Interference Effects. IV. Does a Zero Minimum in Induced Absorption Imply the Proportionality of the Induced Dipole Moment to the Force?

1973 ◽  
Vol 51 (23) ◽  
pp. 2455-2458 ◽  
Author(s):  
J. Courtenay Lewis
Keyword(s):  
Dipole Moment ◽  
Lorentz Gas ◽  
Intermolecular Force ◽  
Interference Effects ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Interference Minimum

We show that, within the limits of the theory of intercollisional interference effects developed for collision-induced absorption by a Lorentz gas in paper I of this series, an intercollisional interference minimum which goes precisely to zero implies that the induced dipole moment is exactly proportional to the intermolecular force.

scholarly journals Elementary Statistical Models for Vector Collision-Sequence Interference Effects with Poisson-Distributed Collision Times

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
John Courtenay Lewis
Keyword(s):  
Dipole Moment ◽  
Poisson Process ◽  
Statistical Models ◽  
Intermolecular Force ◽  
Interference Effects ◽  
Arbitrary Power ◽  
Realistic Estimate ◽  
Induced Dipole ◽  
Using Data

In a recent paper (Lewis, 2008) a class of models suitable for application to collision-sequence interference was introduced. In these models velocities are assumed to be completely randomized in each collision. The distribution of velocities was assumed to be Gaussian. The integrated induced dipole moment μk, for vector interference, or the scalar modulation μk, for scalar interference, was assumed to be a function of the impulse (integrated force) fk, or its magnitude fk, experienced by the molecule in a collision. For most of (Lewis, 2008) it was assumed that μk∝fk and μk∝fk, but it proved to be possible to extend the models, so that the magnitude of the induced dipole moment is equal to an arbitrary power or sum of powers of the intermolecular force. This allows estimates of the infilling of the interference dip by the disproportionality of the induced dipole moment and force. One particular such model, using data from (Herman and Lewis, 2006), leads to the most realistic estimate for the infilling of the vector interference dip yet obtained. In (Lewis, 2008) the drastic assumption was made that collision times occurred at equal intervals. In the present paper that assumption is removed: the collision times are taken to form a Poisson process. This is much more realistic than the equal-intervals assumption. The interference dip is found to be a Lorentzian in this model.

Intensity of the Pressure-Induced Fundamental Infrared Band of Gaseous Chlorine

1973 ◽  
Vol 51 (6) ◽  
pp. 696-697 ◽  
Author(s):  
P. T. T. Wong ◽  
E. Whalley
Keyword(s):  
Dipole Moments ◽  
Good Evidence ◽  
Transition Moment ◽  
Infrared Band ◽  
Fundamental Band ◽  
Induced Dipole ◽  
Integrated Intensity ◽  
Type Interaction

The integrated intensity of the pressure-induced fundamental band of gaseous chlorine measured by Winkel, Hunt, and Clouter is about 5 times that calculated assuming that the transition moment arises from the oscillation of quadrupole-induced dipole moments. This provides good evidence that valence-type interaction between gaseous chlorine molecules occurs.

scholarly journals A Measure of the Interference Effect Distribution

2019 ◽  
Author(s):  
thibault gajdos ◽  
Mathieu Servant ◽  
Thierry Hasbroucq ◽  
Karen Davranche
Keyword(s):  
Experimental Data ◽  
Interference Effect ◽  
Graphical Representation ◽  
Response Times ◽  
Cognitive Model ◽  
Individual Data ◽  
Interference Effects ◽  
Distribution Index

We elaborated an index, the Interference Distribution Index, that allows to quantify the relation between response times and the size of the interference effect. This index is associated to an intuitive graphical representation, the Lorenz-interference plot. We show that this index has some convenient properties in terms of sensitivity to changes in the distribution of the interference effect and to aggregation of individual data. Moreover, it turns out that this index is the only one (up to an arbitrary increasing transformation) possessing these properties. The relevance of this index is illustrated through simulations of a cognitive model of interference effects and reanalysis of experimental data.

scholarly journals Same fold, different properties: polarizable molecular dynamics simulations of telomeric and TERRA G-quadruplexes

2019 ◽  
Vol 48 (2) ◽  
pp. 561-575 ◽  
Author(s):  
Justin A Lemkul
Keyword(s):  
Molecular Dynamics ◽  
Force Field ◽  
Molecular Dynamics Simulations ◽  
Dipole Moments ◽  
Sequence Motifs ◽  
Telomeric Dna ◽  
Rna Sequences ◽  
Dna And Rna ◽  
Induced Dipole ◽  
Dynamics Simulations

Abstract DNA and RNA sequences rich in guanine can fold into noncanonical structures called G-quadruplexes (GQs), which exhibit a common stem structure of Hoogsteen hydrogen-bonded guanine tetrads and diverse loop structures. GQ sequence motifs are overrepresented in promoters, origins of replication, telomeres, and untranslated regions in mRNA, suggesting roles in modulating gene expression and preserving genomic integrity. Given these roles and unique aspects of different structures, GQs are attractive targets for drug design, but greater insight into GQ folding pathways and the interactions stabilizing them is required. Here, we performed molecular dynamics simulations to study two bimolecular GQs, a telomeric DNA GQ and the analogous telomeric repeat-containing RNA (TERRA) GQ. We applied the Drude polarizable force field, which we show outperforms the additive CHARMM36 force field in both ion retention and maintenance of the GQ folds. The polarizable simulations reveal that the GQs bind bulk K+ ions differently, and that the TERRA GQ accumulates more K+ ions, suggesting different ion interactions stabilize these structures. Nucleobase dipole moments vary as a function of position and also contribute to ion binding. Finally, we show that the TERRA GQ is more sensitive than the telomeric DNA GQ to water-mediated modulation of ion-induced dipole-dipole interactions.

Electroactive perovskite lead zirconate particles embedded in an acrylic elastomer

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Nuchnapa Tangboriboon ◽  
Anuvat Sirivat ◽  
Ruksapong Kunanuruksapong ◽  
Sujitra Wongkasemjit
Keyword(s):  
Electric Field ◽  
Storage Modulus ◽  
Volume Fraction ◽  
Dipole Moments ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Additional Stress ◽  
Interparticle Interactions ◽  
Induced Dipole ◽  
Small Volume Fraction

AbstractLead zirconate was synthesized via the sol-gel process and calcined at 300°C for 1 h to obtain a Perovskite structure of an orthorhombic form. SEM micrographs indicate that the lead zirconate particles are moderately dispersed in a solid acrylic rubber, AR71. Without an electric field, the particles merely act as a dielectric filler that can absorb and store additional stress. Under electrical field, particle-induced dipole moments are generated, leading to the interparticle interactions, thus creating a substantial increase in the storage modulus. At the small volume fraction of lead zirconate particles of 0.02 embedded in the elastomer matrix, the electrical conductivity increases dramatically by two orders of magnitude. At the volume fraction of merely 0.0002, the storage modulus, or the composite rigidity, increases by a factor of two as the electric field strength is varied from 0 to 2 kV/mm.

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