On nuclear spin statistics in rotational transition intensities in tetrahedral AB4 molecules

1979 ◽  
Vol 57 (8) ◽  
pp. 1081-1089 ◽  
Author(s):  
Arieh Rosenberg ◽  
Joel Susskind
Keyword(s):  
Dipole Moment ◽  
Nuclear Spin ◽  
Rotational Transition ◽  
Polarizability Tensor ◽  
Centrifugal Distortion ◽  
Induced Dipole ◽  
Integrated Intensity ◽  
Nuclear Spin Statistics ◽  
Tetrahedral Molecules ◽  
Integrated Intensities

A general expression is derived for the integrated intensity of rotational transitions in the vibronic ground state of tetrahedral molecules, taking into account the nuclear spin statistics. It is shown that the ratio of this expression to previously published spin-free integrated intensities depends only on the tensor character N of the operator driving the transition, the appropriate rotational quantum numbers J and J′, and the nuclear spin IB of the identical nuclei. Tables are given for N = 3, 4 and J ≤ 50 which enable the calculation of integrated intensities for octopole and hexadecapole collision induced dipole moment transitions, centrifugal distortion induced dipole moment transitions, and centrifugal distortion induced anisotropic polarizability tensor Raman transitions. It is shown that the relative error of the spin-free integrated intensity calculation is proportional to (2IB + 1)−2.

Pressure-induced absorption in nonpolar gases containing tetrahedral molecules

1976 ◽  
Vol 54 (5) ◽  
pp. 611-617 ◽  
Author(s):  
A. D. Buckingham ◽  
A. J. C. Ladd
Keyword(s):  
Dipole Moment ◽  
Field Gradient ◽  
Infrared Radiation ◽  
Far Infrared ◽  
Spectral Moment ◽  
Induced Absorption ◽  
Integrated Intensity ◽  
Tetrahedral Molecules ◽  
Spherical Molecule ◽  
Far Infrared Radiation

The theory of pressure-induced absorption of far infrared radiation by gases is extended to include the contribution of the dipole moment induced in a molecule by the field gradient due to its neighbours. This dipole is nonzero when the molecule lacks a centre of inversion, as in a tetrahedron. In the collision of two tetrahedra, the dipole induced in molecule 2 by the electric field of the octopole moment Ω1 of the partner leads to transitions in which ΔJ(1) = 0, ± 1, ±2, ±3, and ΔJ(2) = 0. The dipole induced by the field gradient of Ω1 leads to ΔJ(1) = 0, ±1, ±2, ±3, and ΔJ(2) = 0, ±1, ±2, ±3, and therefore gives a required increase in absorption at higher frequencies. The field-gradient contribution vanishes in a collision involving a tetrahedral and a spherical molecule. General expressions are given for the field-gradient contributions to the integrated intensity and to the −2 spectral moment.

scholarly journals Analysis and Mapping of Detailed Inner Information of Crystalline Grain by Wavelength-Resolved Neutron Transmission Imaging with Individual Bragg-Dip Profile-Fitting Analysis

2021 ◽  
Vol 11 (11) ◽  
pp. 5219
Author(s):  
Yosuke Sakurai ◽  
Hirotaka Sato ◽  
Nozomu Adachi ◽  
Satoshi Morooka ◽  
Yoshikazu Todaka ◽  
...  
Keyword(s):  
Crystal Orientation ◽  
Perfect Crystal ◽  
Imaging Method ◽  
Transmission Imaging ◽  
Profile Fitting ◽  
Imaging Results ◽  
Integrated Intensity ◽  
Small Change ◽  
Integrated Intensities ◽  
Pulsed Neutron

As a new method for evaluating single crystals and oligocrystals, pulsed neutron Bragg-dip transmission analysis/imaging method is being developed. In this study, a single Bragg-dip profile-fitting analysis method was newly developed, and applied for analyzing detailed inner information in a crystalline grain position-dependently. In the method, the spectrum profile of a single Bragg-dip is analyzed at each position over a grain. As a result, it is expected that changes in crystal orientation, mosaic spread angle and thickness of a perfect crystal can be evaluated from the wavelength, the width and the integrated intensity of the Bragg-dip, respectively. For confirming this effectiveness, the method was applied to experimental data of position-dependent Bragg-dip transmission spectra of a Si-steel plate consisting of oligocrystals. As a result, inner information of multiple crystalline grains could be visualized and evaluated. The small change in crystal orientation in a grain, about 0.4°, could be observed by imaging the Bragg-dip wavelengths. By imaging the Bragg-dip widths, both another grain and mosaic block in a grain were detected. Furthermore, imaging results of the integrated intensities of Bragg-dips were consistent with the results of Bragg-dip width imaging. These small crystallographic changes have not been observed and visualized by previous Bragg-dip analysis methods.

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.

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.

DIRECTIONAL DIFFUSION OF K ATOMS ON A GaAs(110) SURFACE

2006 ◽  
Vol 05 (06) ◽  
pp. 895-900 ◽  
Author(s):  
NOBUYUKI ISHIDA ◽  
AGUS SUBAGYO ◽  
KAZUHISA SUEOKA
Keyword(s):  
Dipole Moment ◽  
Electric Field ◽  
Radial Direction ◽  
Negative Sample ◽  
Directional Diffusion ◽  
Sample Bias ◽  
Induced Dipole ◽  
High K ◽  
Scanning Area ◽  
The Relationship

We performed STM measurements on the K/GaAs (110) surface with high K coverage. The K atoms gradually disappeared while scanning the tip over the surface at negative sample bias voltage. The phenomenon strongly occurred over the scanning area and can be explained by the field-induced surface diffusion from the scanning area to radial direction. Considering the interaction between the dipole moment of the adsorbed K atoms and the electric field, we discuss the relationship between the static and induced dipole moment of K atoms on a GaAs (110) surface.

Spectra of (H2)2, (D2)2, and H2–D2 Van der Waals Complexes

1974 ◽  
Vol 52 (12) ◽  
pp. 1082-1089 ◽  
Author(s):  
A. R. W. McKellar ◽  
H. L. Welsh
Keyword(s):  
Fine Structure ◽  
Nuclear Spin ◽  
Selection Rule ◽  
Van Der Waals ◽  
Rotational Quantum Number ◽  
Van Der Waals Complexes ◽  
Not Given ◽  
Simple Effect ◽  
Anisotropic Force ◽  
Nuclear Spin Statistics

Spectra due to the Van der Waals complex (H2)2 have been obtained with greatly improved resolution, and analogous spectra of (D2)2 and H2–D2 have been observed. The experiments were conducted with an absorption path of 110 m in a multiple traversal cell at temperatures between 16 and 21 K. The spectra are manifested as fine structure accompanying the single and double H2 (or D2) transitions in the hydrogen (or deuterium) collision induced fundamental band. The observed structure for (H2)2 and H2–D2 can be unambiguously assigned to rotational transitions of the complex governed by the selection rule Δl = ± 1, ± 3, where l is the rotational quantum number of the complex. A detailed analysis must include anisotropic force effects, and is not given here. The spectrum of (D2)2 is complicated, not only by anisotropic force effects, but also by mutual perturbations between the rotational levels of the upper states of corresponding single and double D2 transitions; for this reason, the assignments suggested are somewhat uncertain. An interesting intensity alternation apparent in part of the (D2)2 spectrum is explained as a simple effect of nuclear spin statistics in the pseudodiatomic molecule (D2)2.

The Microwave Spectrum of Silylisothiocyanate, SiH3NCS

1977 ◽  
Vol 32 (5) ◽  
pp. 473-481 ◽  
Author(s):  
K.-F. Dössel ◽  
D. H. Sutter
Keyword(s):  
Dipole Moment ◽  
Stark Effect ◽  
Heavy Atom ◽  
Quadrupole Coupling Constant ◽  
Rotational Transition ◽  
Coupling Constant ◽  
Bending Vibration ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Atom Chain

Abstract The microwave spectra of 15N-and 13C-substituted SiH3NCS were recorded in the frequency region between 8 and 40 GHz. Combining the resulting rotational constants with values obtained previously for other isotopic species, the complete restructure of the heavy atom chain could be determined. This leads to the following rs-bond distances: rC-S = l-5745 Å, rN-C = 1.2208 Å, and rSi-N = 1.6725 Å. From Stark effect splittings the electric dipole moment of the most abun­dant species was determined for the ground vibrational state and for the first excited state of the lowest frequency bending vibration ν10 . The values are <ν10=0 | μz | ν10=0> = 2.38 + 0.02 D and <ν10=1, l=1| μz | ν10=1, l=1>=2.36 ±0.02D. The direction of the dipole moment is discussed. From the quadrupole hyperfinestructure of the J = 2→J′=3 rotational transition the 14N-quadrupole coupling constant could be determined as Xzz=0.75 MHz. The experimental results are compared to CNDO/2 calculations.

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