Theory of collision-induced translational absorption

1968 ◽  
Vol 46 (10) ◽  
pp. 1163-1172 ◽  
Author(s):  
V. F. Sears
Keyword(s):  
Dipole Moment ◽  
Line Shape ◽  
Shape Function ◽  
Interatomic Potential ◽  
Exponential Model ◽  
Rare Gas ◽  
Repulsive Core ◽  
Frequency Range ◽  
Induced Dipole ◽  
Binary Collisions

A theory of the line shape for collision-induced translational absorption in rare-gas mixtures is developed. The reduced line-shape function is expanded in terms of the quantity ρ/σ, typically of the order of 0.1, where ρ is the range of the induced dipole moment and σ is the size of the repulsive core of the interatomic potential. The calculation is based on the special properties of the exponential model for the induced electric dipole moment. The temperature is assumed to be sufficiently high that the motion of the atoms can be treated classically, while the density is assumed to be sufficiently low that only binary collisions are important and intercollisional correlation effects are negligible over the frequency range of interest. A least-squares comparison of theory with experiment yields values for ρ and the magnitude of the induced moment for Ne–Ar and He–Ar pairs.

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.

Collision-induced microwave absorption in gaseous mixtures of various rare gases at 2.3 cm−1

1980 ◽  
Vol 58 (5) ◽  
pp. 633-641 ◽  
Author(s):  
I. R. Dagg ◽  
W. D. Leckie ◽  
L. A. A. Read
Keyword(s):  
Microwave Absorption ◽  
Room Temperature ◽  
Infrared Region ◽  
Exponential Model ◽  
Rare Gas ◽  
Rare Gases ◽  
Gaseous Mixtures ◽  
Induced Dipole ◽  
Upper Limits ◽  
Density Ratios

Collision-induced microwave absorption has been observed at 2.3 cm−1 for the rare gas mixtures Ne–Kr, Ar–Kr, Ar–Xe, and Kr–Xe. The absorption coefficient has been measured at room temperature for density products up to 8000 amagat2 and for various density ratios. These results have been used in conjunction with those of the infrared region to determine more accurately the zeroth moment for each of the spectra and hence have allowed improved values for the induced dipole moment parameters for the exponential model. Upper limits to the absorption in He–Xe and He–Ar mixtures in the microwave region have also been established.

Intercollisional Interference in the S Lines of H2–He Mixtures

1975 ◽  
Vol 53 (10) ◽  
pp. 954-961 ◽  
Author(s):  
J. D. Poll ◽  
J. L. Hunt ◽  
J. W. Mactaggart
Keyword(s):  
Dipole Moment ◽  
Line Shape ◽  
Short Range ◽  
Experimental Results ◽  
Strength Parameter ◽  
Free Molecule ◽  
Fundamental Band ◽  
A Value ◽  
Induced Dipole ◽  
Interference Minimum

Further experimental results on the pressure induced spectrum of normal H2–He in the region of the S(1) branch of the fundamental band are presented. These results show a well-defined minimum at the transition frequency of the free molecule. The S line is found to be the sum of two components. One of these is of essentially the same nature as the Q branch and should therefore show a pronounced intercollisional interference minimum. The second component shows the usual quadrupolar line shape without a minimum. Finally, a value for the strength parameter characterizing the short range component of the induced dipole moment is determined.

Induced dipole moment of physisorbed rare gas atoms

1987 ◽  
Vol 86 (3) ◽  
pp. 1632-1635 ◽  
Author(s):  
D. Van Labeke ◽  
J. M. Vigoureux ◽  
Ph. Grossel
Keyword(s):  
Dipole Moment ◽  
Rare Gas ◽  
Induced Dipole ◽  
Rare Gas Atoms

On the Theory of Collision-Induced Absorption in Rare Gas Mixtures

1971 ◽  
Vol 49 (7) ◽  
pp. 837-847 ◽  
Author(s):  
S. L. Brenner ◽  
D. A. McQuarrie
Keyword(s):  
Absorption Spectrum ◽  
Dipole Moment ◽  
Far Infrared ◽  
Gas Mixtures ◽  
Moment Function ◽  
Rare Gas ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Calculated Equilibrium

The observed far-infrared collision-induced absorption of helium–argon mixtures is used to determine the parameters in an induced-dipole moment function of the form[Formula: see text]It is shown that, with this form of μ(r), the values of the constants μo, ρ, and c7 that are necessary to fit the first two moments of the observed absorption contour are in disagreement with the available theoretical values of these constants. Possible explanations for this disagreement are discussed in the paper. Finally, it is shown that if μ(r) were known, it is possible to obtain an excellent representation of the entire absorption spectrum from a knowledge of only the first three moments, which are easily calculated equilibrium quantities.

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.

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