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. 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.

Sensitized fluorescence in vapors of alkali metals. X. Energy transfer in sodium–sodium collisions

1968 ◽  
Vol 46 (2) ◽  
pp. 125-128 ◽  
Author(s):  
John Pitre ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Alkali Metals ◽  
Sodium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Sodium Atoms ◽  
The Cross ◽  
Detailed Balancing

The total cross sections for 3 2P1/2–3 2P3/2 mixing collisions between excited and unexcited sodium atoms have been determined in a series of sensitized fluorescence experiments with pure sodium vapor at pressures in the range 0–1.6 × 10−5 mm Hg. The cross section Q2(3 2P1/2 ← 3 2P3/2) was found to be 283 Å2 ± 10%. The cross section Q1(3 2P1/2 → 3 2P3/2) = 532 Å2 was obtained from Q2 through the application of the principle of detailed balancing.

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.

Inelastic Collisions between Excited Alkali Atoms and Molecules. VIII. 62P1/2–62P3/2 Mixing and Quenching in Mixtures of Rubidium with H2, HD, D2, N2, CH4, and CD4

1973 ◽  
Vol 51 (3) ◽  
pp. 257-265 ◽  
Author(s):  
I. N. Siara ◽  
L. Krause
Keyword(s):  
Fine Structure ◽  
Cross Sections ◽  
Ground State ◽  
Inelastic Collisions ◽  
Fluorescent Intensity ◽  
Rubidium Vapor ◽  
Sensitized Fluorescence ◽  
Molecular Gases ◽  
Alkali Atoms ◽  
Intensity Ratios

Excitation transfer between the 62P fine-structure substates in rubidium, induced in inelastic collisions with ground-state molecules, has been studied using techniques of sensitized fluorescence. Rubidium vapor in mixtures with various molecular gases was irradiated with each component of the 2P rubidium doublet in turn, and measurements of sensitized-to-resonance fluorescent intensity ratios yielded the following mixing cross sections Q12(2P1/2 → 2P3/2) and Q21(2P1/2 ← 2P3/2), as well as effective quenching cross sections Q1X(2P1/2 → 2XJ″) and Q2X(2P3/2 → 2XJ″). For collisions with H2: Q12(2P1/2 → 2P3/2) = (41 ± 5) Å2; Q21(2P1/2 ← 2P3/2) = (26 ± 3) Å2; Q1X(2P1/2 → 2XJ″) = (36 ± 9) Å2; Q2X(2P3/2 → 2XJ″) = (31 ± 8) Å2. For HD: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (47 ± 13) Å2; Q2X = (38 ± 10) Å2. For D2: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (28 ± 8) Å2; Q2X = (21 ± 7) Å2. For N2: Q12 = (107 ± 15) Å2; Q21 = (70 ± 10) Å2; Q1X = (128 ± 44) Å2; Q2X = (126 ± 33) Å2. For CH4: Q12 = (38 ± 6) Å2; Q21 = (24 ± 3) Å2; Q1X = (129 ± 41) Å2; Q2X = (114 ± 37) Å2. For CD4: Q12 = (52 ± 7) Å2; Q21 = (34 ± 5) Å2; Q1X = (82 ± 30) Å2; Q2X = (76 ± 22) Å2. An analysis of these results suggests the possibility of resonances with various molecular rotational and vibrational transitions.

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. VII. Sensitized fluorescence and quenching in mixtures of rubidium with H2, HD, D2, N2, CH4, CD4, C2H4, and C2.H6

1970 ◽  
Vol 48 (22) ◽  
pp. 2761-2768 ◽  
Author(s):  
E. S. Hrycyshyn ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Photon Counting ◽  
Inelastic Collisions ◽  
Exciting Light ◽  
Rubidium Vapor ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
Order Of Magnitude ◽  
Resonance Doublet ◽  
Intensity Ratios

52P1/2 ↔ 52P3/2 mixing and 52S1/2 ← 52P1/2, 2P3/2 quenching in rubidium, induced in collisions with ground state H2, HD, D2, N2, CH4, CD4, C2H4, and C2H6 molecules, have been investigated using methods of sensitized fluorescence. The rubidium vapor mixed with each of the gases was excited in turn by each component of the rubidium resonance doublet, and the resulting fluorescence, emitted at right angles to the direction of the exciting light, was resolved into the two fine-structure components whose intensity ratios were measured in relation to the gas pressure using photon counting techniques. The measurements yielded the following cross sections for the mixing and quenching collisions.For H2: Q12(2P1/2 → 2P3/2) = 11 Å2, Q21(2P1/2 ← 2P3/2) = 15 Å2, Q10(2S1/2 ← 2P1/2) = 6 Å2, Q20(2S1/2 ← 2P3/2) = 3 Å2.[Formula: see text]The mixing cross sections agree with theoretical values within an order of magnitude.

Sensitized Fluorescence in Vapors of Alkali Atoms XIV. Temperature Dependence of Cross Sections for 72P1/2–72P3/2 Mixing in Cesium, Induced in Collisions with Noble Gas Atoms

1974 ◽  
Vol 52 (11) ◽  
pp. 945-949 ◽  
Author(s):  
I. N. Siara ◽  
H. S. Kwong ◽  
L. Krause
Keyword(s):  
Temperature Dependence ◽  
Cross Sections ◽  
Noble Gas ◽  
Excitation Transfer ◽  
Sensitized Fluorescence ◽  
Alkali Atoms ◽  
Resonance Doublet ◽  
The Cross ◽  
Adiabatic Case

The cross sections for 72P1/2–72P3/2 excitation transfer in cesium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments at temperatures ranging from 405 to 630 K. The cross sections which lie in the range 0.06–20 Å2, exhibit a temperature dependence which, however, is less pronounced than in the more adiabatic case of the cesium resonance doublet.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: VII. ENERGY TRANSFER IN RUBIDIUM–CESIUM COLLISIONS

1966 ◽  
Vol 44 (4) ◽  
pp. 741-751 ◽  
Author(s):  
M. Czajkowski ◽  
D. A. McGillis ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Alkali Metals ◽  
Dominant Role ◽  
Inelastic Collisions ◽  
Cesium Vapor ◽  
Rubidium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Transfer Processes

Sensitized fluorescence in cesium vapor induced by collisions with excited rubidium atoms was investigated in order to determine the total cross sections for inelastic collisions between excited rubidium atoms and cesium atoms in their ground states. The partial pressure of the rubidium vapor in the Rb–Cs mixture was kept below 2 × 10−5 mm Hg in order to eliminate effects due to the trapping of the Rb resonance radiation. The collision cross sections for the various excitation transfer processes are as follows: Q12′(Rb 5 2P1/2 → Cs 6 2P3/2) = 1.5 Å2; Q11′(Rb 5 2P1/2 → Cs 6 2P1/2) = 0.5 Å2; Q22′(Rb 5 2P3/2 → Cs 6 2P3/2) = 0.9 Å2; Q21′(Rb 5 2P3/2 → Cs 6 2P1/2) = 0.3 Å2. The fact that the cross sections are considerably smaller than those for collisions between similar atoms indicates that the Rb–Cs interactions probably involve van der Waals' forces with a much shorter range than exchange forces, which play a dominant role in Rb–Rb or Cs–Cs collisions.

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