Inelastic collisions between excited alkali atoms and molecules IX. An isotope effect in the cross sections for mixing in cesium, induced in collisions with deuterated methanes

Vacuum ◽  
1975 ◽  
Vol 25 (1) ◽  
pp. 43
Keyword(s):  
Isotope Effect ◽  
Cross Sections ◽  
Inelastic Collisions ◽  
Atoms And Molecules ◽  
Alkali Atoms ◽  
The Cross

Inelastic Collisions Between Excited Alkali Atoms and Molecules X. Temperature Dependence of Cross Sections for 2P1/2↔2P3/2 Mixing in Cesium, Induced in Collisions with Deuterated Hydrogens, Ethanes, and Propanes

1974 ◽  
Vol 52 (7) ◽  
pp. 589-591 ◽  
Author(s):  
E. Walentynowicz ◽  
R. A. Phaneuf ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Cross Sections ◽  
Rotational Energy ◽  
Inelastic Collisions ◽  
Atoms And Molecules ◽  
Rotational Energy Transfer ◽  
Alkali Atoms ◽  
The Cross

The dependence on temperature of the cross sections for 2P1/2 ↔ 2P3/2 mixing in cesium, induced in collisions with various deuterated hydrogen, ethane and propane molecules, has been studied in the range 290–650 K. In the cases of hydrogen and ethane, the behavior of the cross sections was found to depend on the degree of deuteration of the molecules. The very large sizes of the mixing cross sections and the isotope effect observed in their variation with temperature, are ascribed to the phenomenon of electronic to rotational energy transfer.

Inelastic Collisions Between Excited Alkali Atoms and Molecules IX. An Isotope Effect in the Cross Sections for 62P1/2↔62P3/2 Mixing in Cesium, Induced in Collisions with Deuterated Methanes

1974 ◽  
Vol 52 (7) ◽  
pp. 584-588 ◽  
Author(s):  
E. Walentynowicz ◽  
R. A. Phaneuf ◽  
W. E. Baylis ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Isotope Effect ◽  
Cross Sections ◽  
Noble Gas ◽  
Inelastic Collisions ◽  
Semiclassical Theory ◽  
Vibrational States ◽  
Rotational Energy Transfer ◽  
Alkali Atoms ◽  
The Cross

The temperature dependence of cross sections for 62P1/2 ↔ 62P3/2 mixing in cesium, induced in collisions with CH4, CH3D, CH2D2, CHD3, and CD4 molecules, has been investigated in a series of sensitized fluorescence experiments over a temperature range 290–650 K. The various cross sections which are of the order of 10−15 cm2, and which exceed similar cross sections for cesium–noble gas collisions by 4 – 6 orders of magnitude, exhibit differences in their variation with temperature. This isotope effect in the collision cross sections is interpreted on the basis of a novel semiclassical theory of electronic to rotational energy transfer. The cross section for mixing induced by collisions with CF4, which was determined in a subsidiary experiment, and which is 2–3 times larger than the methane cross sections, does not show comparable behavior with temperature, probably because the energy transfer takes place to closely lying molecular vibrational states.

Inelastic collisions between excited alkali atoms and molecules. V. Sensitized fluorescence in mixtures of sodium with N2, H2, HD, and D2

1968 ◽  
Vol 46 (19) ◽  
pp. 2127-2131 ◽  
Author(s):  
M. Stupavsky ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Resonance Effect ◽  
Excitation Transfer ◽  
Inelastic Collisions ◽  
Sodium Vapor ◽  
Sensitized Fluorescence ◽  
Atoms And Molecules ◽  
Alkali Atoms ◽  
Exciting Beam

3 2P1/2 ↔ 3 2P3/2 excitation transfer in sodium, induced in inelastic collisions with ground-state N2, H2, HD, and D2 molecules, has been investigated in a series of sensitized fluorescence experiments. Mixtures of sodium vapor at a pressure of 5 × 10−7 Torr, and the gases, were irradiated with each NaD component in turn, and the fluorescence which contained both D components was monitored at right angles to the direction of the exciting beam. Measurements of the relative intensities of the NaD fluorescent components yielded the following collision cross sections for excitation transfer. For Na–N2 collisions: Q12(2P1/2 → P3/2) = 144 Å2, Q21(2P1,2 ← 2P3/2) = 76 Å2 for Na–H2 collisions: Q12 = 80 Å2, Q21 = 42 Å2. For Na–HD collisions: Q12 = 84 Å2, Q21 = 44 Å2. For Na–D2 collisions: Q12 = 98 Å2, Q21 = 52 Å2. The cross sections Q21 exhibit a slight resonance effect between the atomic and molecular rotational transitions.

Inelastic collisions between excited alkali atoms and molecules. VI. Sensitized fluorescence in mixtures of sodium with CH4, CD4, C2H2, C2H4, and C2H6

1969 ◽  
Vol 47 (12) ◽  
pp. 1249-1252 ◽  
Author(s):  
M. Stupavsky ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Inelastic Collisions ◽  
Fluorescent Light ◽  
Molecular Gas ◽  
Sodium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
The Cross ◽  
Good Agreement

The total cross sections for 32P1/2–32P3/2 mixing in sodium, induced in collisions with CH4, CD4, C2H2, C2H4, and C2H6 molecules, have been determined using the method of sensitized fluorescence. The sodium vapor – molecular gas mixtures were irradiated with each NaD component in turn, and the cross sections were obtained from measurements of relative intensities of the two D components present in the fluorescent light. The cross sections are as follows. For CH4: Q12(2P1/2 → 2P3/2) = 148 Å2, Q21(2P1/2 ← 2P3/2) = 77 Å2; for CD4: Q12 = 151 Å2, Q21 = 81 Å2; for C2H2: Q12 = 182 Å2, Q21 = 96 Å2; for C2H4: Q12 = 178 Å2, Q21 = 94 Å2; for C2H6: Q12 = 182 Å2, Q21 = 95 Å2. The cross sections Q21 are in good agreement with the values calculated according to the theory of Callaway and Bauer.

Inelastic collisions between excited alkali atoms and molecules, III. Sensitized fluorescence and quenching in mixtures of potassium with N2, H2, HD, and D2

1968 ◽  
Vol 46 (1) ◽  
pp. 25-32 ◽  
Author(s):  
D. A. McGillis ◽  
L. Krause
Keyword(s):  
Vapor Pressure ◽  
Cross Sections ◽  
Inelastic Collisions ◽  
Sensitized Fluorescence ◽  
Atoms And Molecules ◽  
Radiation Trapping ◽  
Alkali Atoms ◽  
Resonance Doublet ◽  
Potassium Vapor

4 2P1/2–4 2P3/2 mixing in potassium, induced by collisions with N2, H2, D2, and HD, was studied using techniques of sensitized fluorescence. The potassium vapor-gas systems, in which the potassium vapor pressure was kept very low to avoid radiation trapping, was irradiated with one component of the resonance doublet. The fluorescence which contained both components of the doublet was monitored at right angles to the direction of excitation. The following cross sections for mixing and quenching were obtained from measurements of relative intensities of the fluorescent components. For K–N2 collisions: Q12(2P1/2 → 2P3/2) = 100 Å2, Q21(2P1/2 ← 2P3/2) = 66 Å2, Q10(2S1/2 ← 2P1/2) = 35 Å2, Q20(2S1/2 ←2P3/2) = 39 Å2. For K–H2 collisions: Q12 = 76 Å2, Q21 = 53 Å2, Q10 = 7 Å2, Q20 = 4 Å2. For K–D2: Q12 = 72 Å2, Q21 = 50 Å2, Q10 = 2 Å2, Q20 = 1 Å2. For K–HD: Q12 = 74 Å2, Q21 = 49 Å2, Q20 = 11 Å2, Q20 = 14 Å2. An analysis of these results suggests the presence of resonances with the molecular rotational levels.

Inelastic collisions at low energies

1969 ◽  
Vol 47 (10) ◽  
pp. 1723-1729 ◽  
Author(s):  
A. Dalgarno
Keyword(s):  
Energy Loss ◽  
Cross Sections ◽  
Low Energy ◽  
Inelastic Collisions ◽  
Low Energies ◽  
Low Energy Electrons ◽  
The Cross ◽  
Loss Rates

A summary is presented of the processes by which low energy electrons lose energy in moving through the atmosphere and estimates are given of the cross sections and energy loss rates. The mechanisms by which thermal electrons cool are described and the cooling efficiencies are listed.

Dynamics of theQ2Πu1(1)state studied from the isotope effect on the cross sections for the formation of the2patom pair in the photoexcitation ofH2andD2

2016 ◽  
Vol 93 (6) ◽  
Author(s):  
Kouichi Hosaka ◽  
Kennichi Shiino ◽  
Yuko Nakanishi ◽  
Takeshi Odagiri ◽  
Masashi Kitajima ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Cross Sections ◽  
The Cross

Importance of coupling for inelastic collisions between protons and hydrogen atoms

1965 ◽  
Vol 283 (1392) ◽  
pp. 100-114 ◽  
Keyword(s):  
Cross Sections ◽  
Intermediate State ◽  
Relative Velocity ◽  
Inelastic Collisions ◽  
Hydrogen Atoms ◽  
Resonance Reactions ◽  
The Cross ◽  
Good Agreement

The importance of coupling for fast collisions between protons and hydrogen atoms is examined with the two-centred expansion in atomic eigenfunctions proposed by Bates (1958 a ). Cross-sections are evaluated for reactions H + + H (I s ) → H(I s ) + H + , H + + H( I s ) → H(2 s ) + H + , and H + + H(l a ) → H + + H(2 s ). The effect of a single intermediate state, either I s or 2 s , is considered. For the non-resonance processes, it is found that the cross-sections may be substantially increased by passage through intermediate state for incident energies less than about 10 keV, tending towards equality with decrease in relative velocity. Results obtained for the symmetrical resonance reactions are in good agreement with the two-state solutions of McCarroll (1961).

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: VIII. ENERGY TRANSFER BETWEEN THE 4 2P LEVELS IN POTASSIUM INDUCED BY INELASTIC COLLISIONS

1966 ◽  
Vol 44 (4) ◽  
pp. 753-768 ◽  
Author(s):  
G. D. Chapman ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Alkali Metals ◽  
Inelastic Collisions ◽  
Inert Gases ◽  
Inert Gas ◽  
Vapor Pressures ◽  
Sensitized Fluorescence ◽  
Potassium Vapor ◽  
The Cross ◽  
Scattering Cross Sections

Sensitized fluorescence in potassium vapor and its mixtures with inert gases was investigated in order to determine cross sections for the inelastic collisions leading to excitation transfer between the 4 2P1/2 and 4 2P3/2 states in potassium. The study was carried out at potassium vapor pressures of about 10−6 mm Hg, which were not formerly accessible to such experiments, and in the absence of radiation trapping. The cross sections Q1(4 2P1/2 → 42P3/2) and Q2(4 2P1/2 → 4 2P3/2) are as follows: for K–K collisions: 370 and 250 Å2; for K–He: 60 and 41 Å2; for K–Ne: 14 and 9.5 Å2; for K–A: 37 and 22 Å2; for K–Kr: 61 and 41 Å2; for K–Xe: 104 and 72 Å2. These values supersede those published previously (Chapman, Krause, and Brockman 1964; Chapman and Krause 1965). The cross sections for collisions between potassium and inert gas atoms do not increase monotonically with the polarizabilities of the inert gases but behave similarly to the electron – inert gas elastic scattering cross sections. This behavior is interpreted on the basis of a semiclassical model for the interaction, which involves overlap forces.

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