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.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: VI. ENERGY TRANSFER IN COLLISIONS BETWEEN RUBIDIUM AND INERT GAS ATOMS

1966 ◽  
Vol 44 (4) ◽  
pp. 731-740 ◽  
Author(s):  
Bruce Pitre ◽  
A. G. A. Rae ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Alkali Metals ◽  
Free Particle ◽  
Particle Interaction ◽  
Inert Gases ◽  
Inert Gas ◽  
Sensitized Fluorescence ◽  
Orbital Electron ◽  
The Cross ◽  
Three Body

The total cross sections for inelastic collisions between rubidium and inert gas atoms, leading to a transfer of excitation between the 5 2P1/2 and 5 2P3/2 levels in rubidium, have been determined in a study of sensitized fluorescence in rubidium – inert gas mixtures. The experiments were performed at a rubidium vapor pressure of 1.5 × 10−6 mm Hg, at which there is no imprisonment of resonance radiation, and over a range of inert gas pressures extending from 1 to 350 mm Hg. The cross sections Q1(5 2P1/2 → 5 2P3/2) and Q2(5 2P1/2 ← 5 2P3/2) are as follows: Rb–He: 7.6 × 10−18 and 10.3 × 10−18 cm2; Rb–Ne: 1.7 × 10−19 and 2.3 × 10−19 cm2; Rb–A: 1.0 × 10−19 and 1.6 × 10−19 cm2; Rb–Kr: 6.4 × 10−20 and 1.5 × 10−19 cm2; Rb–Xe: 7.9 × 10−20 and 2.1 × 10−19 cm2. The cross sections are subject to two apparent anomalies: they do not vary monotonically with the polarizabilities of the inert gases and not all of their ratios Q1/Q2 have values predicted by the principle of detailed balancing. These properties of the cross sections, as well as a partial disagreement with Franck's rule, are interpreted qualitatively in terms of a "free particle" interaction between the inert gas atoms and the 5 2P orbital electron in rubidium. A competing process involving three-body collisions and the possible formation of Rb – inert gas van der Waals' molecules is also suggested.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: I. ENERGY TRANSFER IN POTASSIUM–POTASSIUM COLLISIONS

1964 ◽  
Vol 42 (3) ◽  
pp. 535-547 ◽  
Author(s):  
G. D. Chapman ◽  
L. Krause ◽  
I. H. Brockman
Keyword(s):  
Energy Transfer ◽  
Cross Sections ◽  
Alkali Metals ◽  
Experimental Results ◽  
Fluorescent Light ◽  
Vapor Pressures ◽  
Selection Rules ◽  
Sensitized Fluorescence ◽  
Photoelectric Recording ◽  
Potassium Vapor

Sensitized fluorescence in potassium vapor at pressures between 10−5 mm Hg and 10−1 mm Hg was investigated to determine the cross sections for collisions of the second kind between unexcited and excited potassium atoms. An idealized fluorescence tube was used in the experiment and the fluorescent light was analyzed with a photoelectric recording spectrometer. The collision cross sections at low vapor pressures, where imprisonment of radiation is absent, are identical for both the 42P1/2 → 42P3/2 and 42P1/2 ← 42P3/2 transitions and equal 6.6 × 10−12 cm2 at 2 × 10−4 mm Hg. The experimental results are interpreted on the basis of new selection rules for sensitized fluorescence.

Sensitized fluorescence in vapors of alkali metals. XI Energy transfer in potassium–rubidium collisions

1969 ◽  
Vol 47 (2) ◽  
pp. 215-221 ◽  
Author(s):  
E. S. Hrycyshyn ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Cross Sections ◽  
Alkali Metals ◽  
Inelastic Collisions ◽  
Rubidium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Transfer Processes ◽  
Potassium Vapor

Sensitized fluorescence in rubidium vapor, induced by collisions with excited potassium atoms, was investigated to determine the total cross sections for inelastic collisions between excited potassium atoms and rubidium atoms in their ground states. The collision cross sections for the various excitation transfer processes are as follows: Q12′ (K42P1/2 → Rb52P3/2) = 40 Å2, Q22′ (K42P3/2 → Rb52P3/2) = 27 Å2, Q11′ (K42P1/2 → Rb52P1/2) = 2.7 Å2, and Q21′ (K42P3/2 → Rb52P1/2) = 1.9 Å2. The partial pressure of potassium vapor in the K–Rb mixture was kept largely below 10−5 mm Hg to eliminate effects due to the trapping of potassium resonance radiation.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: IX. ENERGY TRANSFER IN COLLISIONS BETWEEN SODIUM AND INERT GAS ATOMS

1967 ◽  
Vol 45 (8) ◽  
pp. 2671-2681 ◽  
Author(s):  
John Pitre ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Alkali Metals ◽  
Inert Gas ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Order Of Magnitude ◽  
The Cross ◽  
Predicted Values ◽  
Detailed Balancing ◽  
Gas Pressures

The total cross sections for inelastic collisions between sodium and inert gas atoms, leading to 3 2P1/2 ↔ 3 2P3/2 excitation transfer in sodium, have been determined in a series of sensitized fluorescence experiments with sodium – inert gas mixtures. The sodium vapor was maintained at a pressure of 5 × 10−7 mm Hg, at which there is no trapping of the resonance radiation, and the inert gas pressures ranged from 0 to 1 mm Hg. The cross sections Q1(3 2P1/2 → 3 2P3/2) and Q2(3 2P1/2 ← 3 2P3/2) are as follows: Na–He, 86.0 and 44.8 Å2; Na–Ne, 67.0 and 35.4 Å2; Na–Ar, 110 and 55.9 Å2; Na–Kr, 85.0 and 43.6 Å2; Na–Xe, 89.8 and 45.6 Å2. The ratios Q1/Q2 are in agreement with the value predicted from the principle of detailed balancing and the cross sections also agree, as to order of magnitude, with some theoretically predicted values.

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.

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.

Sensitized fluorescence in vapors of alkali metals. XII. 42P1/2–42P3/2 mixing in potassium, induced in collisions with ground-state rubidium atoms

1969 ◽  
Vol 47 (2) ◽  
pp. 223-226 ◽  
Author(s):  
E. S. Hrycyshyn ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Alkali Metals ◽  
Resonance Radiation ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Partial Pressures ◽  
Potassium Vapor ◽  
Detailed Balancing

The total cross sections for collisions between excited potassium and unexcited rubidium atoms, leading to the transfer of excitation between the 42P states in potassium, have been determined in a sensitized fluorescence experiment. The experiments were carried out at partial pressures of potassium vapor lower than 10−5 mm Hg, at which the imprisonment of resonance radiation may be disregarded. The cross sections Q12″ (42P1/2 → 42P3/2) and Q21″ (42P1/2 ← 42P3/2) equal 260 Å2 and 175 Å2, respectively, and are in the ratio predicted by the principle of detailed balancing.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: V. ENERGY TRANSFER IN COLLISIONS BETWEEN CESIUM AND INERT GAS ATOMS

1966 ◽  
Vol 44 (1) ◽  
pp. 91-103 ◽  
Author(s):  
M. Czajkowski ◽  
D. A. McGillis ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Cross Sections ◽  
Alkali Metals ◽  
Free Particle ◽  
Excitation Transfer ◽  
Inert Gas ◽  
Cesium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Gas Pressures

The total cross sections for excitation transfer between the 6 2P1/2 and 6 2P3/2 levels in cesium, induced by collisions of the second kind between cesium and inert gas atoms, have been determined using methods of sensitized fluorescence. The experiments were carried out at a cesium vapor pressure of 1 × 10−6 mm Hg, at which there is no trapping of resonance radiation, and over a range of inert gas pressures extending from 1 to 300 mm Hg. The cross sections Q1(2P1/2 → P3/2) and Q2(2P1/2 ← 2P3/2) are as follows: Cs–He: 5.7 × 10−21 and 3.9 × 10−20 cm2; Cs–Ne: 1.9 × 10−21 and 3.1 × 10−20 cm2; Cs–A: 1.6 × 10−21 and 5.2 × 10−20 cm2; Cs–Kr: 8.3 × 10−21 and 18.4 × 10−20 cm2; Cs–Xe: 7.2 × 10−21 and 27.4 × 10−20 cm2. A mechanism for the excitation transfer is suggested, which involves an interaction between the inert gas atoms and the 6 2P electron in cesium, behaving as a free particle.

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

1965 ◽  
Vol 43 (9) ◽  
pp. 1574-1588 ◽  
Author(s):  
A. G. A. Rae ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Cross Sections ◽  
Alkali Metals ◽  
Photon Counting ◽  
Vapor Pressures ◽  
Rubidium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Detailed Balancing

Sensitized fluorescence in rubidium vapor has been investigated in order to determine total cross sections for collisions of the second kind between rubidium atoms, leading to the transfer of excitation between the 52P1/2and 52P3/2resonance levels. The experiments were carried out at vapor pressures below 10−5 mm Hg, where there is virtually no imprisonment of resonance radiation. The exceedingly low fluorescent intensities were registered in an automatically programmed sequence of measurements, using photon counting techniques. The cross sections Q1(52P1/2 → 52P3/2) and Q2(52P1/2 ← 52P3/2) equal 53 Å2and 68 Å2respectively at 87 °C and 60 Å2and 72 Å2respectively at 107 °C. At both temperatures the ratios Q1/Q2are in agreement with the values predicted by the principle of detailed balancing.

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: II. ENERGY TRANSFER IN POTASSIUM–ARGON COLLISIONS

1965 ◽  
Vol 43 (4) ◽  
pp. 563-575 ◽  
Author(s):  
G. D. Chapman ◽  
L. Krause
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Alkali Metals ◽  
Average Lifetime ◽  
Sensitized Fluorescence ◽  
Exact Agreement ◽  
Collision Cross Sections ◽  
Potassium Vapor ◽  
Transfer Mechanisms ◽  
Detailed Balancing

Sensitized fluorescence in potassium, induced by argon at pressures between 0.01 mm Hg and 350 mm Hg, was investigated to determine the cross sections for collisions of the second kind between potassium atoms in the 4 2P states and argon atoms in their ground states. The experiment was carried out at a potassium vapor pressure of 2 × 10−6 mm Hg at which there is no trapping of resonance radiation. The collision cross sections at very low argon pressures, at which the collision frequencies do not exceed one per average lifetime of the excited states, are Q1 = 10 × 10−15 cm2 for the 4 2P1/2 → 4 2P3/2 transition and Q2 = 7.2 × 10−15 cm2 for the 4 2P1/2 ←  4 2P3/2 transition. At higher pressures, where the collisions are much more frequent, Q1 = 1.8 × 10−15 cm2, Q2 = 1.1 × 10−15 cm2, and Q1/Q2 = 1.6, in exact agreement with the principle of detailed balancing. The variation of the collision cross sections with argon pressure is ascribed to different transfer mechanisms predominating in the various pressure regions.

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