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Canadian Journal of Physics

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

E. S. Hrycyshyn, L. Krause

Published Jan 15, 1969• 9 citations
Publisher

Abstract

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.

DOI
10.1139/p69-026

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

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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.

Canadian Journal of Physics•Jan 15, 1969•15 citations

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

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Canadian Journal of Physics•Sep 1, 1965•11 citations

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

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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.

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Sensitized Fluorescence in Vapors of Alkali Atoms. XIII. 62P1/2−62P3/2 Excitation Transfer in Rubidium, Induced in Collisions with Noble Gas Atoms

I. N. Siara, E. S. Hrycyshyn, L. Krause

The cross sections for excitation transfer between the 62P fine-structure substates in rubidium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments. Mixtures of rubidium vapor and noble gases at pressures varying in the range 0–5 Torr were irradiated with each component of the second 2P rubidium doublet in turn and the following cross sections for 2P mixing were obtained from measurements of sensitised-to-resonance fluorescent intensity ratios. Rb–He: Q12(2P1/2 → 2P3/2) = 29.3 Å2; Q21(2P1/2 ← 2P3/2) = 19.0 Å2. Rb–Ne: Q12 = 10.3 Å2; Q21 = 6.4 Å2. Rb–Ar: Q12 = 24.0 Å2; Q21 = 14.9 Å2. Rb–Kr: Q12 = 23.2 Å2; Q21 = 14.6 Å2. Rb–Xe: Q12 = 43.9 Å2; Q21 = 27.7 Å2 In their dependence on the magnitude of the fine-structure splitting, the values are consistent with previously determined cross sections for mixing in the first and third 2P doublets of alkali atoms.

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

G. D. Chapman, L. Krause

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.

Canadian Journal of Physics•Apr 1, 1965•12 citations
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 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 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 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 5 2P1/2 and 5 2P3/2 resonance 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(5 2P1/2 → 52P3/2) and Q2(5 2P1/2 ← 5 2P3/2) equal 53 Å2 and 68 Å2 respectively at 87 °C and 60 Å2 and 72 Å2 respectively at 107 °C. At both temperatures the ratios Q1/Q2 are in agreement with the values predicted by the principle of detailed balancing.
The cross sections for excitation transfer between the 62P fine-structure substates in rubidium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments. Mixtures of rubidium vapor and noble gases at pressures varying in the range 0–5 Torr were irradiated with each component of the second 2P rubidium doublet in turn and the following cross sections for 2P mixing were obtained from measurements of sensitised-to-resonance fluorescent intensity ratios. Rb–He: Q12(2P1/2 → 2P3/2) = 29.3 Å2; Q21(2P1/2 ← 2P3/2) = 19.0 Å2. Rb–Ne: Q12 = 10.3 Å2; Q21 = 6.4 Å2. Rb–Ar: Q12 = 24.0 Å2; Q21 = 14.9 Å2. Rb–Kr: Q12 = 23.2 Å2; Q21 = 14.6 Å2. Rb–Xe: Q12 = 43.9 Å2; Q21 = 27.7 Å2 In their dependence on the magnitude of the fine-structure splitting, the values are consistent with previously determined cross sections for mixing in the first and third 2P doublets of alkali atoms.
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.